| 1. |
- Abrahamsson, Tobias, et al.
(författare)
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Investigating the role of polymer size on ionic conductivity in free-standing hyperbranched polyelectrolyte membranes
- 2021
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Ingår i: Polymer. - : Elsevier. - 0032-3861 .- 1873-2291. ; 223
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Tidskriftsartikel (refereegranskat)abstract
- Polymer-based ion exchange membranes (IEMs) are utilized for many applications such as in water desalination, energy storage, fuel cells and in electrophoretic drug delivery devices, exemplified by the organic electronic ion pump (OEIP). The bulk of current research is primarily focused on finding highly conductive and stable IEM materials. Even though great progress has been made, a lack of fundamental understanding of how specific polymer properties affect ionic transport capabilities still remains. This leads to uncertainty in how to proceed with synthetic approaches for designing better IEM materials. In this study, an investigation of the structure-property relationship between polymer size and ionic conductivity was performed by comparing a series of membranes, based on ionically charged hyperbranched polyglycerol of different polymer sizes. Observing an increase in ionic conductivity associated with increasing polymer size and greater electrolyte exclusion, indi-cating an ionic transportation phenomenon not exclusively based on membrane electrolyte uptake. These findings further our understanding of ion transport phenomena in semi-permeable membranes and indicate a strong starting point for future design and synthesis of IEM polymers to achieve broader capabilities for a variety of ion transport-based applications.
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| 2. |
- Arbring Sjöström, Theresia, et al.
(författare)
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Cross-Linked Polyelectrolyte for Improved Selectivity and Processability of lontronic Systems
- 2017
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 9:36, s. 30247-30252
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Tidskriftsartikel (refereegranskat)abstract
- On-demand local release of biomolecules enables fine-tuned stimulation for the next generation of neuromodulation therapies. Such chemical stimulation is achievable using iontronic devices based on microfabricated, highly selective ion exchange membranes (IEMs). Current limitations in processability and performance of thin film LEMs hamper future developments of this technology. Here we address this limitation by developing a cationic IEM with excellent processability and ionic selectivity: poly(4-styrenesulfonic acidco-maleic acid) (PSS-co-MA) cross-linked with polyethylene glycol (PEG). This enables new design opportunities and provides enhanced compatibility with in vitro cell studies. PSSA-co-MA/PEG is shown to out-perform the cation selectivity of the previously used iontronic material.
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| 3. |
- Arbring Sjöström, Theresia, 1987-, et al.
(författare)
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Design and Operation of Hybrid Microfluidic Iontronic Probes for Regulated Drug Delivery
- 2021
-
Ingår i: Advanced Materials Technologies. - Hoboken, New Jersey : John Wiley & Sons. - 2365-709X. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Highly controlled drug delivery devices play an increasingly important role in the development of new neuroengineering tools. Stringent - and sometimes contradicting - demands are placed on such devices, ranging from robustness in freestanding devices, to overall device miniaturization, while maintaining precise spatiotemporal control of delivery with high chemical specificity and high on/off ratio. Here, design principles of a hybrid microfluidic iontronic probe that uses flow for long-range pressure-driven transport in combination with an iontronic tip that provides electronically fine-tuned pressure-free delivery are explored. Employing a computational model, the effects of decoupling the drug reservoir by exchanging a large passive reservoir with a smaller microfluidic system are reported. The transition at the microfluidic-iontronic interface is found to require an expanded ion exchange membrane inlet in combination with a constant fluidic flow, to allow a broad range of device operation, including low source concentrations and high delivery currents. Complementary to these findings, the free-standing hybrid probe monitored in real time by an external sensor is demonstrated. From these computational and experimental results, key design principles for iontronic devices are outlined that seek to use the efficient transport enabled by microfluidics, and further, key observations of hybrid microfluidic iontronic probes are explained.
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| 4. |
- Arbring Sjöström, Theresia, et al.
(författare)
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Miniaturized Ionic Polarization Diodes for Neurotransmitter Release at Synaptic Speeds
- 2020
-
Ingår i: Advanced Materials Technologies. - : WILEY. - 2365-709X. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Current neural interfaces rely on electrical stimulation pulses to affect neural tissue. The development of a chemical delivery technology, which can stimulate neural tissue with the bodys own set of signaling molecules, would provide a new level of sophistication in neural interfaces. Such technology should ideally provide highly local chemical delivery points that operate at synaptic speed, something that is yet to be accomplished. Here, the development of a miniaturized ionic polarization diode that exhibits many of the desirable properties for a chemical neural interface technology is reported. The ionic diode shows proper diode rectification and the current switches from off to on in 50 mu s at physiologically relevant electrolyte concentrations. A device model is developed to explain the characteristics of the ionic diode in more detail. In combination with experimental data, the model predicts that the ionic polarization diode has a delivery delay of 5 ms to reach physiologically relevant neurotransmitter concentrations at subcellular spatial resolution. The model further predicts that delays of amp;lt;1 ms can be reached by further miniaturization of the diode geometry. Altogether, the results show that ionic polarization diodes are a promising building block for the next generation of chemical neural interfaces.
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| 5. |
- Arbring Sjöström, Theresia, 1987-
(författare)
-
Organic Bioelectronics for Neurotransmitter Release at the Speed of Life
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The signaling dynamics in neuronal networks includes processes ranging from lifelong neuromodulation to direct synaptic neurotransmission. In chemical synapses, the time delay it takes to pass a signal from one neuron to the next lasts for less than a millisecond. At the post-synaptic neuron, further signaling is either up- or down-regulated, dependent on the specific neurotransmitter and receptor. While this up- and down-regulation of signals usually runs perfectly well and enables complex performance, even a minor dysfunction of this signaling system can cause major complications, in the shape of neurological disorders. The field of organic bioelectronics has the ability to interface neurons with high spatiotemporal recording and stimulation techniques. Local chemical stimulation, i.e. local release of neurotransmitters, enables the possibility of artificially altering the chemical environment in dysfunctional signaling pathways to regain or restore neural function. To successfully interface the biological nervous system with electronics, a range of demands must be met. Organic bioelectronic techniques and materials are capable of reaching the demands on the biological as well as the electronic side of the interface. These demands span from high performance biocompatible materials, to miniaturized and specific device architectures, and high dose control on demand within milliseconds.The content of this thesis is a continuation of the development of organic bioelectronic devices for neurotransmitter delivery. Organic materials are utilized to electrically control the dose of charged neurotransmitters by translating electric charge into controlled artificial release. The first part of the thesis, Papers 1 and 2, includes further development of the resistor-type release device called the organic electronic ion pump. This part includes material evaluation, microfluidic incorporation, and device design considerations. The aim for the second part of this thesis, Papers 3 and 4, is to enhance temporal performance, i.e. reduce the delay between electrical signal and neurotransmitter delivery to corresponding delay in biological neural signaling, while retaining tight dosage control. Diffusion of neurotransmitters between nerve cells is a slow process, but since it is restricted to short distances, the total time delay is short. In our organic bioelectronic devices, several orders of magnitude in speed can be gained by switching from lateral to vertical delivery geometries. This is realized by two different types of vertical diodes combined with a lateral preload and waste configuration. The vertical diode assembly was further expanded with a control electrode that enables individual addressing in each of several combined release sites. These integrated circuits allow for release of neurotransmitters with high on/off release ratios, approaching delivery times on par with biological neurotransmission.
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| 6. |
- Berggren, Magnus, Professor, 1968-, et al.
(författare)
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In Vivo Organic Bioelectronics for Neuromodulation
- 2022
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Ingår i: Chemical Reviews. - : American Chemical Society (ACS). - 0009-2665 .- 1520-6890. ; 122:4, s. 4826-4846
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Forskningsöversikt (refereegranskat)abstract
- The nervous system poses a grand challenge for integration with modern electronics and the subsequent advances in neurobiology, neuroprosthetics, and therapy which would become possible upon such integration. Due to its extreme complexity, multifaceted signaling pathways, and similar to 1 kHz operating frequency, modern complementary metal oxide semiconductor (CMOS) based electronics appear to be the only technology platform at hand for such integration. However, conventional CMOS-based electronics rely exclusively on electronic signaling and therefore require an additional technology platform to translate electronic signals into the language of neurobiology. Organic electronics are just such a technology platform, capable of converting electronic addressing into a variety of signals matching the endogenous signaling of the nervous system while simultaneously possessing favorable material similarities with nervous tissue. In this review, we introduce a variety of organic material platforms and signaling modalities specifically designed for this role as "translator" , focusing especially on recent implementation in in vivo neuromodulation. We hope that this review serves both as an informational resource and as an encouragement and challenge to the field.
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| 7. |
- Berggren, Magnus, et al.
(författare)
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Ion Electron-Coupled Functionality in Materials and Devices Based on Conjugated Polymers
- 2019
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Ingår i: Advanced Materials. - : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 31:22
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Forskningsöversikt (refereegranskat)abstract
- The coupling between charge accumulation in a conjugated polymer and the ionic charge compensation, provided from an electrolyte, defines the mode of operation in a vast array of different organic electrochemical devices. The most explored mixed organic ion-electron conductor, serving as the active electrode in these devices, is poly(3,4-ethyelenedioxythiophene) doped with polystyrelensulfonate (PEDOT:PSS). In this progress report, scientists of the Laboratory of Organic Electronics at Linkoping University review some of the achievements derived over the last two decades in the field of organic electrochemical devices, in particular including PEDOT:PSS as the active material. The recently established understanding of the volumetric capacitance and the mixed ion-electron charge transport properties of PEDOT are described along with examples of various devices and phenomena utilizing this ion-electron coupling, such as the organic electrochemical transistor, ionic-electronic thermodiffusion, electrochromic devices, surface switches, and more. One of the pioneers in this exciting research field is Prof. Olle Inganas and the authors of this progress report wish to celebrate and acknowledge all the fantastic achievements and inspiration accomplished by Prof. Inganas all since 1981.
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| 8. |
- Berggren, Magnus, 1968-, et al.
(författare)
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Organic bioelectronics based on Mixed Ion–Electron conductors
- 2019. - 4
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Ingår i: Conjugated polymers. - Boca Raton : CRC Press. - 9780429190520 ; , s. 679-696
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter focuses on two specific areas of organic mixed ion–electron conductors: surfaces and scaffolds for controlling cell cultures, and “iontronic”-controlled delivery of ions and biomolecules. It draws on iontronic technology based on ion exchange materials, which is compatible with physiological salt concentrations. Iontronics is attractive for bioelectronic applications, as it provides a means for the manipulation of flows of ions and charged biomolecules – species that can possess chemical and biological functionality. The organic electronic ion pump (OEIP) is a delivery device where charged (bio)molecules are transported within a polyelectrolyte membrane. The electronic control of the delivery flux, together with micrometer-sized channel outlets, enables OEIPs to achieve high spatiotemporal resolution; biomolecule delivery can be tightly controlled to a specific site and dose amount. High spatiotemporal control of ion and biomolecule concentrations is attractive for a wide range of in vitro studies of biological systems.??
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| 9. |
- Bernacka Wojcik, Iwona, et al.
(författare)
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Flexible Organic Electronic Ion Pump for Flow-Free Phytohormone Delivery into Vasculature of Intact Plants
- 2023
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Ingår i: Advanced Science. - : WILEY. - 2198-3844. ; 10:14
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Tidskriftsartikel (refereegranskat)abstract
- Plant vasculature transports molecules that play a crucial role in plant signaling including systemic responses and acclimation to diverse environmental conditions. Targeted controlled delivery of molecules to the vascular tissue can be a biomimetic way to induce long distance responses, providing a new tool for the fundamental studies and engineering of stress-tolerant plants. Here, a flexible organic electronic ion pump, an electrophoretic delivery device, for controlled delivery of phytohormones directly in plant vascular tissue is developed. The c-OEIP is based on polyimide-coated glass capillaries that significantly enhance the mechanical robustness of these microscale devices while being minimally disruptive for the plant. The polyelectrolyte channel is based on low-cost and commercially available precursors that can be photocured with blue light, establishing much cheaper and safer system than the state-of-the-art. To trigger OEIP-induced plant response, the phytohormone abscisic acid (ABA) in the petiole of intact Arabidopsis plants is delivered. ABA is one of the main phytohormones involved in plant stress responses and induces stomata closure under drought conditions to reduce water loss and prevent wilting. The OEIP-mediated ABA delivery triggered fast and long-lasting stomata closure far away from the delivery point demonstrating systemic vascular transport of the delivered ABA, verified delivering deuterium-labeled ABA.
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| 10. |
- Bernacka Wojcik, Iwona, et al.
(författare)
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Implantable Organic Electronic Ion Pump Enables ABA Hormone Delivery for Control of Stomata in an Intact Tobacco Plant
- 2019
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Ingår i: Small. - : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 15:43
-
Tidskriftsartikel (refereegranskat)abstract
- Electronic control of biological processes with bioelectronic devices holds promise for sophisticated regulation of physiology, for gaining fundamental understanding of biological systems, providing new therapeutic solutions, and digitally mediating adaptations of organisms to external factors. The organic electronic ion pump (OEIP) provides a unique means for electronically-controlled, flow-free delivery of ions, and biomolecules at cellular scale. Here, a miniaturized OEIP device based on glass capillary fibers (c-OEIP) is implanted in a biological organism. The capillary form factor at the sub-100 mu m scale of the device enables it to be implanted in soft tissue, while its hyperbranched polyelectrolyte channel and addressing protocol allows efficient delivery of a large aromatic molecule. In the first example of an implantable bioelectronic device in plants, the c-OEIP readily penetrates the leaf of an intact tobacco plant with no significant wound response (evaluated up to 24 h) and effectively delivers the hormone abscisic acid (ABA) into the leaf apoplast. OEIP-mediated delivery of ABA, the phytohormone that regulates plants tolerance to stress, induces closure of stomata, the microscopic pores in leafs epidermis that play a vital role in photosynthesis and transpiration. Efficient and localized ABA delivery reveals previously unreported kinetics of ABA-induced signal propagation.
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| 11. |
- Boda, Ulrika, et al.
(författare)
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Fully Screen-Printed Stretchable Organic Electrochemical Transistors
- 2023
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Ingår i: Advanced Materials Technologies. - : John Wiley and Sons Inc. - 2365-709X. ; :16
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Tidskriftsartikel (refereegranskat)abstract
- Stretchable organic electrochemical transistors (OECTs) are promising for wearable applications within biosensing, bio-signal recording, and addressing circuitry. Efficient large-scale fabrication of OECTs can be performed with printing methods but to date there are no reports on high-performance fully printed stretchable OECTs. Herein, this challenge is addressed by developing fully screen-printed stretchable OECTs based on an architecture that minimizes electrochemical side reactions and improves long-term stability. Fabrication of the OECTs is enabled by in-house development of three stretchable functional screen-printing inks and related printing processes. The stretchable OECTs show good characteristics in terms of transfer curves, output characteristics, and transient response up to 100% static strain and 500 strain cycles at 25% and 50% strain. The strain insensitivity of the OECTs can be further improved by strain conditioning, resulting in stable performance up to 50% strain. Finally, an electrochromic smart pixel is demonstrated by connecting a stretchable OECT to a stretchable electrochromic display. It is believed that the development of screen-printed stretchable electrochemical devices, and OECTs in particular, will pave the way for their use in wearable applications and commercial products. © 2023 The Authors.
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| 12. |
- Boda, Ulrika, et al.
(författare)
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Screen-Printed Corrosion-Resistant and Long-Term Stable Stretchable Electronics Based on AgAu Microflake Conductors
- 2023
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society. - 1944-8244 .- 1944-8252. ; 15:9, s. 12372-
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Tidskriftsartikel (refereegranskat)abstract
- High-throughput production methods such as screen printing can bring stretchable electronics out of the lab into the market. Most stretchable conductor inks for screen printing are based on silver nanoparticles or flakes due to their favorable performance-to-cost ratio, but silver is prone to tarnishing and corrosion, thereby limiting the stability of such conductors. Here, we report on a cost-efficient and scalable approach to resolve this issue by developing screen printable inks based on silver flakes chemically coated by a thin layer of gold. The printed stretchable AgAu conductors reach a conductivity of 8500 S cm-1, remain conductive up to 250% strain, show excellent corrosion and tarnishing stability, and are used to demonstrate wearable LED and NFC circuits. The reported approach is attractive for smart clothing, as the long-term functionality of such devices is expected in a variety of environments. © 2023 The Authors.
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| 13. |
- Boda, Ulrika, 1990-
(författare)
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Screen Printed Stretchable Electronics
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wearable electronics that can be seamlessly integrated into clothing, onto skin, or inside the body, can enable a variety of novel applications within healthcare monitoring, biosensing, biomedical devices and the internet of things. Seamless integration requires matching of the mechanical properties of the electronics to clothing, skin, and tissues, i.e., the electronics need to be soft, flexible, and stretchable. One approach to achieve this is to make all or most components of a device stretchable in themselves by developing functional intrinsically stretchable composites. Such composites are typically based on a filler, which provides electronic or other functionality, and an elastomer matrix, which provides the mechanical properties of the composites. Manufacturing of intrinsically stretchable electronics is challenging and often involve time consuming and tedious fabrication procedures of low throughput, based on chemically harmful monomers and solvents. An alternative approach, printing of electronics, has experienced a boom in the past decade, recently even for stretchable applications. However, despite its appeal, stretchable printed electronic products have yet to reach the consumer market in larger numbers. Screen printing is a versatile printing method that is cost-effective, scalable, can be tailored to use harmless solvents with little waste, and can be made environmentally friendly by careful choice of materials. Furthermore, some applications of stretchable technology – such as implants and on-skin electronics – require conductors that are stable under humid, corrosive, or polluted conditions, which puts even more weight into choices of ink components.In paper I, we protected readily available conducting silver flakes through a thin coating with gold in a low-toxicity water-based process and demonstrated its use in inks for screen printed corrosion-resistant stretchable conductors. The novel silver-gold flake ink was used to fabricate a functional stretchable near-field communication device. Papers II and III both concern entirely screen printed and inherently stretchable devices, utilizing novel stretchable inks in combination with commercial inks to print vertical stacks. Two electrochemical devices – electrochromic displays and organic electrochemical transistors – were printed and tested under stretched conditions to push the limits of how screen printing can be used in applications for thin and stretchable wearable technology. The results show that the devices can retain electrical function even under practically high strains of 50 % (display) and 100 % (transistor). Finally, in paper IV, we investigate the operational principle of gold nanowire- based stretchable composites and find that interactions on the nano-and microscale differ between composites using the same filler but different elastomers. This study sheds light on the importance of the type of elastomer chosen for composites, as this heavily influences the composite’s electrical performance under strain.Altogether, the studies presented in this thesis provide knowledge, materials, and processes that in the long run can contribute to more effective devices within healthcare and other wearable electronics applications.
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| 14. |
- Cherian, Dennis, 1989-
(författare)
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Expanding the versatility and functionality of iontronic devices
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biological systems rarely use electrons as signal regulators, most of the transport and communication in these system utilize ions. The discovery of conjugated polymers and polyelectrolytes and their unique properties of mixed ionic electronic properties opened the possibility of using these in the domain of bioelectronics, which paved the way for the field of organic bioelectronics. After the introduction of the organic electronic ion pump (OEIP) in 2007, which utilizes both the ionic properties of conjugated polymers and polyelectrolytes, the new field of “iontronics” evolved. TheOEIP is an organic polymer-based delivery system based on electrophoretic transport of biologically relevant and ionically charged species, without fluid flow and with high spatial, temporal, and dosage precision. These devices have been extensivelystudied for the past 14 years and have found numerous demonstrations in in vivo and in vitro delivery of bio-relevant ions for therapeutic application. This has, in parallel, resulted in the development of custom materials for ion exchange membranes (IEMs) within the OEIP.This thesis focuses on IEMs and device development of OEIPs. Specific focus is given to process development through device design and fabrication through conventional and unconventional technologies. Conventional technologies include microfabrication through photolithography, etching, and thin-film evaporation. Unconventional fabrication techniques include screen printing, inkjet printing, stencil, and laser patterning. In this thesis, we have also scouted a new area of research to utilize the ion-selective properties of polyelectrolytes. Here we discuss a new ion detection technique using IEMs and ion transport based on diffusion coefficients and impedance measurement at a specific frequency using impedance spectroscopy for faster ion detection with low voltage (1–40 V) and liquid-flow-free transport. Further exploring the area of IEMs, we have realized that less attention has been given to stretchable IEMs, even though such materials could find enormous applications in the field of organic bioelectronics and can be used in association with many stretchable electronics applications like stretchable displays and energy storage devices. Current IEMs lack the conformability and stretchability to be used for implantable applications, e.g., including lungs, heart, muscle, soft or brain implants, joints, etc. Keeping this in mind we also discuss our approach for the development of a stretchable IEM. Finally, we focus on developing a hybrid fabrication protocol of flexible OEIPs with micropatterning techniques and inkjet-printed membranes. These OEIPs were fabricated and the functionality was validated by the cell response after the delivery of a nerve-blocking agent to cells in vitro. To date, OEIPs have been fabricated by micropatterning and labor-intensive manual techniques, impeding the budding application areas of this propitious technology. To address this issue, a novel approach to the fabrication of the OEIPs using screen-printing technology is also explored in this thesis. In summary, we were able to successfully explore the field of ion-exchange membranesand put forward a new technique for ion detection and stretchable IEMs for future applications. Fabrication of OEIPs was also examined which resulted in the development of a hybrid fabrication protocol with inkjet printing for OEIPs and a robust fully screen printed OEIPs with high manufacturing yield (>90%) for industrial-scale manufacturing.
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| 15. |
- Cherian, Dennis, 1989-, et al.
(författare)
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Flexible Organic Electronic Ion Pump Fabricated Using Inkjet Printing and Microfabrication for Precision In Vitro Delivery of Bupivacaine
- 2023
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Ingår i: Advanced Healthcare Materials. - : John Wiley and Sons Inc. - 2192-2640 .- 2192-2659. ; 12:24, s. 2300550-
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Tidskriftsartikel (refereegranskat)abstract
- The organic electronic ion pump (OEIP) is an on-demand electrophoretic drug delivery device, that via electronic to ionic signal conversion enables drug delivery without additional pressure or volume changes. The fundamental component of OEIPs is their polyelectrolyte membranes which are shaped into ionic channels that conduct and deliver ionic drugs, with high spatiotemporal resolution. The patterning of these membranes is essential in OEIP devices and is typically achieved using laborious microprocessing techniques. Here, the development of an inkjet printable formulation of polyelectrolyte is reported, based on a custom anionically functionalized hyperbranched polyglycerol (i-AHPG). This polyelectrolyte ink greatly simplifies the fabrication process and is used in the production of free-standing OEIPs on flexible polyimide (PI) substrates. Both i-AHPG and the OEIP devices are characterized, exhibiting favorable iontronic characteristics of charge selectivity and the ability to transport aromatic compounds. Further, the applicability of these technologies is demonstrated by the transport and delivery of the pharmaceutical compound bupivacaine to dorsal root ganglion cells with high spatial precision and effective nerve blocking, highlighting the applicability of these technologies for biomedical scenarios. © 2023 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH.
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| 16. |
- Cherian, Dennis, et al.
(författare)
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Large-area printed organic electronic ion pumps
- 2019
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Ingår i: FLEXIBLE AND PRINTED ELECTRONICS. - : IOP PUBLISHING LTD. - 2058-8585. ; 4:2
-
Tidskriftsartikel (refereegranskat)abstract
- Biological systems use a large variety of ions and molecules of different sizes for signaling. Precise electronic regulation of biological systems therefore requires an interface which translates the electronic signals into chemically specific biological signals. One technology for this purpose that has been developed during the last decade is the organic electronic ion pump (OEIP). To date, OEIPs have been fabricated by micropatterning and labor-intensive manual techniques, hindering the potential application areas of this promising technology. Here we show, for the first time, fully screen-printed OEIPs. We demonstrate a large-area printed design with manufacturing yield amp;gt;90%. Screen-printed cation- and anion-exchange membranes are both demonstrated with promising ion selectivity and performance, with transport verified for both small ions (Na+,K+,Cl-) and biologically-relevant molecules (the cationic neurotransmitter acetylcholine, and the anionic anti-inflammatory salicylic acid). These advances open the iontronics toolbox to the world of printed electronics, paving the way for a broader arena for applications.
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| 17. |
- Cherian, Dennis, et al.
(författare)
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Soft iontronic delivery devices based on an intrinsically stretchable ion selective membrane
- 2021
-
Ingår i: Flexible and Printed Electronics. - : IOP Publishing Ltd. - 2058-8585. ; 6:4
-
Tidskriftsartikel (refereegranskat)abstract
- Implantable electronically controlled drug delivery devices can provide precision therapeutic treatments by highly spatiotemporally controlled delivery. Iontronic delivery devices rely on the movement of ions rather than liquid, and can therefore achieve electronically controlled precision delivery in a compact setting without disturbing the microenvironment within the tissue with fluid flow. For maximum precision, the delivery device needs to be closely integrated into the tissue, which is challenging due to the mechanical mismatch between the soft tissue and the harder devices. Here we address this challenge by developing a soft and stretchable iontronic delivery device. By formulating an ink based on an in-house synthesized hyperbranched polyelectrolyte, water dispersed polyurethane, and a thickening agent, a viscous ink is developed for stencil patterning of soft ion exchange membranes (IEMs). We use this ink for developing soft and stretchable delivery devices, which are characterized both in the relaxed and stretched state. We find that their functionality is preserved up to 100% strain, with small variations in resistance due to the strain. Finally, we develop a skin patch to demonstrate the outstanding conformability of the developed device. The presented technology is attractive for future soft implantable delivery devices, and the stretchable IEMs may also find applications within wearable energy devices.
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| 18. |
- Delavari, Najmeh, et al.
(författare)
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Nernst-Planck-Poisson analysis of electrolyte-gated organic field-effect transistors
- 2021
-
Ingår i: Journal of Physics D. - : IOP PUBLISHING LTD. - 0022-3727 .- 1361-6463. ; 54:41
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Tidskriftsartikel (refereegranskat)abstract
- Electrolyte-gated organic field-effect transistors (EGOFETs) represent a class of organic thin-film transistors suited for sensing and biosensing in aqueous media, often at physiological conditions. The EGOFET device includes electrodes and an organic semiconductor channel in direct contact with an electrolyte. Upon operation, electric double layers are formed along the gate-electrolyte and the channel-electrolyte interfaces, but ions do not penetrate the channel. This mode of operation allows the EGOFET devices to run at low voltages and at a speed corresponding to the rate of forming electric double layers. Currently, there is a lack of a detailed quantitative model of the EGOFETs that can predict device performance based on geometry and material parameters. In the present paper, for the first time, an EGOFET model is proposed utilizing the Nernst-Planck-Poisson equations to describe, on equal footing, both the polymer and the electrolyte regions of the device configuration. The generated calculations exhibit semi-qualitative agreement with experimentally measured output and transfer curves.
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| 19. |
- Duan, Yulong, et al.
(författare)
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Tuneable Anisotropic Plasmonics with Shape-Symmetric Conducting Polymer Nanoantennas
- 2023
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095.
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Tidskriftsartikel (refereegranskat)abstract
- A wide range of nanophotonic applications rely on polarization-dependent plasmonic resonances, which usually requires metallic nanostructures that have anisotropic shape. This work demonstrates polarization-dependent plasmonic resonances instead by breaking symmetry via material permittivity. The study shows that molecular alignment of a conducting polymer can lead to a material with polarization-dependent plasma frequency and corresponding in-plane hyperbolic permittivity region. This result is not expected based only on anisotropic charge mobility but implies that also the effective mass of the charge carriers becomes anisotropic upon polymer alignment. This unique feature is used to demonstrate circularly symmetric nanoantennas that provide different plasmonic resonances parallel and perpendicular to the alignment direction. The nanoantennas are further tuneable via the redox state of the polymer. Importantly, polymer alignment could blueshift the plasma wavelength and resonances by several hundreds of nanometers, forming a novel approach toward reaching the ultimate goal of redox-tunable conducting polymer nanoantennas for visible light. Traditional anisotropic nanoantennas have asymmetric shape. In this work, symmetry is instead broken by straining of a conducting polymer, leading to an in-plane anisotropic plasma frequency. This enables circularly symmetric nanoantennas with polarization-dependent localized surface plasmon resonances. The polarization dependence is consistent with inverse changes of the effective mass and mobility of thecharge carriers along different in-plane directions.image
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| 20. |
- Forro, Csaba, et al.
(författare)
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Predictive Model for the Electrical Transport within Nanowire Networks
- 2018
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 12:11, s. 11080-11087
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Tidskriftsartikel (refereegranskat)abstract
- Thin networks of high aspect ratio conductive nanowires can combine high electrical conductivity with excellent optical transparency, which has led to a widespread use of nanowires in transparent electrodes, transistors, sensors, and flexible and stretchable conductors. Although the material and application aspects of conductive nanowire films have been thoroughly explored, there is still no model which can relate fundamental physical quantities, like wire resistance, contact resistance, and nanowire density, to the sheet resistance of the film. Here, we derive an analytical model for the electrical conduction within nanowire networks based on an analysis of the parallel resistor network. The model captures the transport characteristics and fits a wide range of experimental data, allowing for the determination of physical parameters and performance-limiting factors, in sharp contrast to the commonly employed percolation theory. The model thus constitutes a useful tool with predictive power for the evaluation and optimization of nanowire networks in various applications.
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| 21. |
- Forro, Csaba, et al.
(författare)
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Visualizing and Analyzing 3D Metal Nanowire Networks for Stretchable Electronics
- 2020
-
Ingår i: Advanced Theory and Simulations. - : John Wiley & Sons. - 2513-0390. ; 3:8
-
Tidskriftsartikel (refereegranskat)abstract
- Composites based on conductive nanowires embedded in elastomers are popular in a wide range of stretchable electronics applications where the requirements are either a stable or a highly increasing electrical resistance upon strain. Despite the widespread use of such composites, their production is not based in solid theoretical grounds but rather in empirical observations. The lack of such a framework is due to limitations in the methods for studying nanowire meshes, in particular the lack of knowledge on the spatial distribution of the nanowires and the change of their position under strain. This hurdle is overcome by collecting 3D reconstructed X-ray tomographies of silver nanowires embedded in polydimethylsiloxane (PDMS) under variable deformations and the missing structural information of the nanomaterial is obtained by unsupervised artificial intelligence image analysis. This allowed to reveal the precise assembly mechanisms of nanowire systems and derive a precise analytical formula for the piezoresistive response of the composite and finally to simulate the behavior of arbitrary samples in-silico.
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| 22. |
- Gabrielsson, Erik O., 1985-, et al.
(författare)
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A Four-Diode Full-Wave Ionic Current Rectifier Based on Bipolar Membranes : Overcoming the Limit of Electrode Capacity
- 2014
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Ingår i: Advanced Materials. - : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 26:30, s. 5143-5147
-
Tidskriftsartikel (refereegranskat)abstract
- Full-wave rectification of ionic currents is obtained by constructing the typical four-diode bridge out of ion conducting bipolar membranes. Together with conjugated polymer electrodes addressed with alternating current, the bridge allows for generation of a controlled ionic direct current for extended periods of time without the production of toxic species or gas typically arising from electrode side-reactions.
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| 23. |
- Gabrielsson, Erik O., et al.
(författare)
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Ion diode logics for pH control
- 2012
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Ingår i: Lab on a Chip. - Cambridge, UK : Royal Society of Chemistry. - 1473-0197 .- 1473-0189. ; 12:14, s. 2507-2513
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Tidskriftsartikel (refereegranskat)abstract
- Electronic control over the generation, transport, and delivery of ions is useful in order to regulate reactions, functions, and processes in various chemical and biological systems. Different kinds of ion diodes and transistors that exhibit non-linear current versus voltage characteristics have been explored to generate chemical gradients and signals. Bipolar membranes (BMs) exhibit both ion current rectification and water splitting and are thus suitable as ion diodes for the regulation of pH. To date, fast switching ion diodes have been difficult to realize due to accumulation of ions inside the device structure at forward bias – charges that take a long time to deplete at reverse bias. Water splitting occurs at elevated reverse voltage bias and is a feature that renders high ion current rectification impossible. This makes integration of ion diodes in circuits difficult. Here, we report three different designs of micro-fabricated ion bipolar membrane diodes (IBMDs). The first two designs consist of single BM configurations, and are capable of either splitting water or providing high current rectification. In the third design, water-splitting BMs and a highly-rectifying BM are connected in series, thus suppressing accumulation of ions. The resulting IBMD shows less hysteresis, faster off-switching, and also a high ion current rectification ratio as compared to the single BM devices. Further, the IBMD was integrated in a diode-based AND gate, which is capable of controlling delivery of hydroxide ions into a receiving reservoir.
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| 24. |
- Gabrielsson, Erik O., 1985-, et al.
(författare)
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Polyphosphonium-Based Ion Bipolar Junction Transistors
- 2014
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 8:6, s. 064116-
-
Tidskriftsartikel (refereegranskat)abstract
- Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons, but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e. ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2 μm, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example addressable drug-delivery devices.
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| 25. |
- Gabrielsson, Erik O, et al.
(författare)
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Spatially Controlled Amyloid Reactions Using Organic Electronics
- 2010
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Ingår i: SMALL. - : John Wiley and Sons, Ltd. - 1613-6810. ; 6:19, s. 2153-2161
-
Tidskriftsartikel (refereegranskat)abstract
- Abnormal protein aggregates, so called amyloid fibrils, are mainly known as pathological hallmarks of a wide range of diseases, but in addition these robust well-ordered self-assembled natural nanostructures can also be utilized for creating distinct nanomaterials for bioelectronic devices. However, current methods for producing amyloid fibrils in vitro offer no spatial control. Herein, we demonstrate a new way to produce and spatially control the assembly of amyloid-like structures using an organic electronic ion pump (OEIP) to pump distinct cations to a reservoir containing a negatively charged polypeptide. The morphology and kinetics of the created proteinaceous nanomaterials depends on the ion and current used, which we leveraged to create layers incorporating different conjugated thiophene derivatives, one fluorescent (p-FTAA) and one conducting (PEDOT-S). We anticipate that this new application for the OEIP will be useful for both biological studies of amyloid assembly and fibrillogenesis as well as for creating new bioelectronic nanomaterials and devices.
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| 26. |
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| 27. |
- Jonsson, Amanda, et al.
(författare)
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Chemical delivery array with millisecond neurotransmitter release
- 2016
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Ingår i: Science Advances. - Washington : American Association for the Advancement of Science (A A A S). - 2375-2548. ; 2:11
-
Tidskriftsartikel (refereegranskat)abstract
- Technologies that restore or augment dysfunctional neural signaling represent a promising route to deeper understanding and new therapies for neurological disorders. Because of the chemical specificity and subsecond signaling of the nervous system, these technologies should be able to release specific neurotransmitters at specific locations with millisecond resolution. We have previously demonstrated an organic electronic lateral electrophoresis technology capable of precise delivery of charged compounds, such as neurotransmitters. However, this technology, the organic electronic ion pump, has been limited to a single delivery point, or several simultaneously addressed outlets, with switch-on speeds of seconds. We report on a vertical neurotransmitter delivery device, configured as an array with individually controlled delivery points and a temporal resolution of 50 ms. This is achieved by supplementing lateral electrophoresis with a control electrode and an ion diode at each delivery point to allow addressing and limit leakage. By delivering local pulses of neurotransmitters with spatiotemporal dynamics approaching synaptic function, the high-speed delivery array promises unprecedented access to neural signaling and a path toward biochemically regulated neural prostheses.
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| 28. |
- Karakurt, Nuri, et al.
(författare)
-
Thermoelectric Properties of Flexible PEDOT/PU and PEDOT/PVDF Films
- 2019
-
Ingår i: CENTRAL EUROPEAN SYMPOSIUM ON THERMOPHYSICS 2019 (CEST). - : AMER INST PHYSICS. - 9780735418769
-
Konferensbidrag (refereegranskat)abstract
- The growing energy demands for wearable electronic devices has shifted the attention of scientific community towards flexible thermoelectric materials and devices; the main goal being the enhancement of the thermoelectric and conducting properties of such systems, without sacrificing their flexibility. This paper reports the enhancement of the thermoelectric properties of flexible Poly(3,4-ethylenedioxythiophene), (PEDOT), films with acid (HCl) exposure. Relative high conductive, flexible and uniform PEDOT/polyurethane(PU) and (PEDOT)/polyvinylidene fluoride (PVDF) films were prepared, separately. The films were dipped into acid solution with the exposure time of 5, 10, and 15 min. The sheet resistance (Omega/sq), electrical conductivity (sigma), Seebeck coefficient (S) and thermoelectric power factor (sigma S-2) were measured for those systems. The thermoelectric behavior of both films was optimized with different exposure times in acid solution, while the thermoelectric properties of the PEDOT/PVDF films remained unchanged with this treatment. The Seebeck coefficient and thermoelectric power of PEDOT/PU enhanced from 9.01 to 12.6 mu V/K and from 7.4x10(-2) to 12.2x10(-2) mu W/mK(2), respectively for a 10 min exposure. The origin of this enhancement was tracked down to modifications in the surface morphology of the films, identified through AFM microscopy. The presented results indicate that acid treatment is a potential and promising approach to enhance the thermoelectric properties of PEDOT/PU films for flexible, conformable and low-cost TE applications.
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| 29. |
- Keene, Scott T., et al.
(författare)
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Exploiting mixed conducting polymers in organic and bioelectronic devices
- 2022
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 24:32, s. 19144-19163
-
Forskningsöversikt (refereegranskat)abstract
- Efficient transport of both ionic and electronic charges in conjugated polymers (CPs) has enabled a wide range of novel electrochemical devices spanning applications from energy storage to bioelectronic devices. In this Perspective, we provide an overview of the fundamental physical processes which underlie the operation of mixed conducting polymer (MCP) devices. While charge injection and transport have been studied extensively in both ionic and electronic conductors, translating these principles to mixed conducting systems proves challenging due to the complex relationships among the individual materials properties. We break down the process of electrochemical (de)doping, the basic feature exploited in mixed conducting devices, into its key steps, highlighting recent advances in the study of these physical processes in the context of MCPs. Furthermore, we identify remaining challenges in further extending fundamental understanding of MCP-based device operation. Ultimately, a deeper understanding of the elementary processes governing operation in MCPs will drive the advancement in both materials design and device performance.
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| 30. |
- Kim, Nara, et al.
(författare)
-
An intrinsically stretchable symmetric organic battery based on plant-derived redox molecules
- 2023
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:46, s. 25703-25714
-
Tidskriftsartikel (refereegranskat)abstract
- Intrinsically stretchable energy storage devices are essential for the powering of imperceptible wearable electronics. Organic batteries based on plant-derived redox-active molecules can offer critical advantages from a safety, sustainability, and economic perspective, but such batteries are not yet available in soft and stretchable form factors. Here we report an intrinsically stretchable organic battery made of elastomeric composite electrodes formulated with alizarin, a natural dye derived from the plant Rubia tinctorum, whose two quinone motifs enable its uses in both positive and negative electrodes. The quaternary biocomposite electrodes possess excellent electron-ion conduction/coupling and superior stretchability (>300%) owing to self-organized hierarchical morphology. In a full-cell configuration, its energy density of 3.8 mW h cm−3 was preserved at 100% strain, and assembled modules on stretchy textiles and rubber gloves can power integrated LEDs during various deformations. This work paves the way for low-cost, eco-friendly, and deformable batteries for next generation wearable electronics.
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| 31. |
- Kim, Nara, et al.
(författare)
-
Elastic conducting polymer composites in thermoelectric modules
- 2020
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- The rapid growth of wearables has created a demand for lightweight, elastic and conformal energy harvesting and storage devices. The conducting polymer poly(3,4-ethylenedioxythiophene) has shown great promise for thermoelectric generators, however, the thick layers of pristine poly(3,4-ethylenedioxythiophene) required for effective energy harvesting are too hard and brittle for seamless integration into wearables. Poly(3,4-ethylenedioxythiophene)-elastomer composites have been developed to improve its mechanical properties, although so far without simultaneously achieving softness, high electrical conductivity, and stretchability. Here we report an aqueously processed poly(3,4-ethylenedioxythiophene)-polyurethane-ionic liquid composite, which combines high conductivity (>140Scm(-1)) with superior stretchability (>600%), elasticity, and low Youngs modulus (<7MPa). The outstanding performance of this organic nanocomposite is the result of favorable percolation networks on the nano- and micro-scale and the plasticizing effect of the ionic liquid. The elastic thermoelectric material is implemented in the first reported intrinsically stretchable organic thermoelectric module. Though deformable thermoelectric materials are desirable for integrating thermoelectric devices into wearable electronics, typical thermoelectric materials are too brittle for practical application. Here, the authors report a high-performance elastic composite for stretchable thermoelectric modules.
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| 32. |
- Li, Changbai, et al.
(författare)
-
Engineering Conductive Hydrogels with Tissue-like Properties: A 3D Bioprinting and Enzymatic Polymerization Approach
- 2024
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Ingår i: Small Science. - : WILEY. - 2688-4046. ; In Press
-
Tidskriftsartikel (refereegranskat)abstract
- Hydrogels are promising materials for medical devices interfacing with neural tissues due to their similar mechanical properties. Traditional hydrogel-based bio-interfaces lack sufficient electrical conductivity, relying on low ionic conductivity, which limits signal transduction distance. Conducting polymer hydrogels offer enhanced ionic and electronic conductivities and biocompatibility but often face challenges in processability and require aggressive polymerization methods. Herein, we demonstrate in situ enzymatic polymerization of π-conjugated monomers in a hyaluronan (HA)-based hydrogel bioink to create cell-compatible, electrically conductive hydrogel structures. These structures were fabricated using 3D bioprinting of HA-based bioinks loaded with conjugated monomers, followed by enzymatic polymerization via horseradish peroxidase. This process increased the hydrogels’ stiffness from about 0.6 to 1.5 kPa and modified their electroactivity. The components and polymerization process were well-tolerated by human primary dermal fibroblasts and PC12 cells. This work presents a novel method to fabricate cytocompatible and conductive hydrogels suitable for bioprinting. These hybrid materials combine tissue-like mechanical properties with mixed ionic and electronic conductivity, providing new ways to use electricity to influence cell behavior in a native-like microenvironment.
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| 33. |
- Lienemann, Samuel, et al.
(författare)
-
A Soft and Stretchable Multielectrode Cuff for Selective Peripheral Nerve Stimulation
- 2023
-
Ingår i: Advanced Materials Technologies. - : WILEY. - 2365-709X. ; 8:6
-
Tidskriftsartikel (refereegranskat)abstract
- Bioelectronic medicine can treat diseases and disorders in humans by electrically interfacing with peripheral nerves. Multielectrode cuffs can be used for selective stimulation of portions of the nerve, which is advantageous for treatment specificity. The biocompatibility and conformability of cuffs can be improved by reducing the mechanical mismatch between nerve tissue and cuffs, but selective stimulation of nerves has yet to be achieved with soft and stretchable cuff electrodes. Here, this paper reports the development of a soft and stretchable multielectrode cuff (sMEC) for selective nerve stimulation. The device is made of 50 mu m thick silicone with embedded gold nanowire conductors, which renders it functional at 50% strain, and provides superior conformability for wrapping nerves. By using different stimulation protocols, high functional selectivity is achieved with the sMECs eight stimulation electrodes in a porcine sciatic nerve model. Finite element modeling is used to predict the potential distribution within the nerve, which correlate well with the achieved stimulation results. Recent studies are showing that mechanical softness is of outermost importance for reducing foreign body response. It is therefore believed that the soft high-performance sMEC technology is ideal for future selective peripheral nerve interfaces for bioelectronic medicine.
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| 34. |
- Lienemann, Samuel, et al.
(författare)
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Exploring the Elastomer Influence on the Electromechanical Performance of Stretchable Conductors
- 2024
-
Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 16:29, s. 38365-38376
-
Tidskriftsartikel (refereegranskat)abstract
- Stretchable electronics has received major attention in recent years due to the prospects of integrating electronics onto and into the human body. While many studies investigate how different conductive fillers perform in stretchable composites, the effect of different elastomers on composite performance, and the related fundamental understanding of what is causing the performance differences, is poorly understood. Here, we perform a systematic investigation of the elastomer influence on the electromechanical performance of gold nanowire-based stretchable conductors based on five chemically different elastomers of similar Young's modulus. The choice of elastomer has a huge impact on the electromechanical performance of the conductors under cyclic strain, as some composites perform well, while others fail rapidly at 100% strain cycling. The lack of macroscopic crack formation in the failing composites indicates that the key aspect for good electromechanical performance is not homogeneous films on the macroscale but rather beneficial interactions on the nanoscale. Based on the comprehensive characterization, we propose a failure mechanism related to the mechanical properties of the elastomers. By improving our understanding of elastomer influence on the mechanisms of electrical failure, we can move toward rational material design, which could greatly benefit the field of stretchable electronics.
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| 35. |
- Lienemann, Samuel Lukas, 1988-
(författare)
-
Materials and Devices for Stretchable Electronic Nerve Interfaces
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Within our body, there is a large network of nerves that facilitates communication between the brain and the body’s organs. This network is called our peripheral nervous system, consisting of soft and stretchable nerve bundles that gradually increase in their functional specificity as they split and branch out the closer they get to their target organ. Communication within the nerve is based on action potentials, fast fluctuations in electric trans-membrane potential along the neurons within the nerve. These action potentials can be recorded and artificially triggered by interfacing electronically with peripheral nerves. In doing so, modern medicine is able to elucidate the mechanisms behind disorders related to the nervous system and even applies novel electronic therapies to treat them. Over the last decade, the field of biomedical engineering has therefore seen a surge of interest in electronic devices that interface with the peripheral nervous system, such as cuff electrodes. The device function is based on electrodes that are implanted in close proximity of the nerves they intend to record or stimulate. A cuff electrode, specifically, is wrapped around a peripheral nerve and applies stimulation pulses at electrodes located on the inside of the cuff to evoke action potentials within the nerve. Our body is not welcoming to foreign objects though. Any implant within our body triggers a foreign body reaction with an intensity dependent on the biocompatibility of the implant. Recent studies have found that one of the major factors governing the foreign body reaction is the mechanical mismatch of the implant to the interfacing tissue, with softer, more mechanically similar implants, exhibiting reduced foreign body response. This has prompted an ongoing push for thin and soft peripheral nerve interfaces. However, to truly match the mechanical properties of peripheral nerves, peripheral nerve interfaces need not only to be soft and flexible, they need to become as elastic and stretchable as the nerve themselves. A common strategy to achieve stretchable conductors is by incorporating highly conductive filler materials in an elastomeric matrix. The resulting composite remains conductive even when stretched due to the ability of the filler material to dislocate with the elastomeric matrix while retaining its interconnectivity and thus conductivity. Electronic composites based on gold nanowires and silicones are promising candidates for stretchable peripheral nerve interfaces, due to their material-based biocompatibility, good stretchability, and versatile patterning possibilities.Based on this, the thesis at hand investigated stretchable electronic composite materials and devices to interface with the peripheral nervous system. Publication I and II develop gold-nanowire/polydimethylsiloxane-based cuff electrodes, which are functional even at 50% strain, as peripheral nerve interfaces in vivo. These publications highlight the beneficial conformability of stretchable devices, with a stretchable bi-polar cuff for low-voltage stimulation of the rat sciatic nerve in publication I and a stretchable multi-electrode cuff for selective stimulation of the pig sciatic nerve in publication II. Publication III investigates stretchable gold-nanowire composites based on a variety of elastomers, therein, elucidating the influence of the varying elastomer properties on the electromechanical performance of gold-nanowire composites. Lastly, publication IV establishes a stretchable ion delivery device with potential use for the peripheral nervous system. The device is based on an ionically conductive membrane as the conductive filler, and the device can be reversibly stretched to 100% strain. Overall, this thesis presents stretchable materials and devices that advance the possibilities for peripheral nerve interfaces.
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| 36. |
- Lienemann, Samuel, et al.
(författare)
-
Stretchable gold nanowire-based cuff electrodes for low-voltage peripheral nerve stimulation
- 2021
-
Ingår i: Journal of Neural Engineering. - : IOP PUBLISHING LTD. - 1741-2560 .- 1741-2552. ; 18:4
-
Tidskriftsartikel (refereegranskat)abstract
- Objective. Electrical stimulation of the peripheral nervous system (PNS) can treat various diseases and disorders, including the healing process after nerve injury. A major challenge when designing electrodes for PNS stimulation is the mechanical mismatch between the nerve and the device, which can lead to non-conformal contact, tissue damage and inefficient stimulation due to current leakage. Soft and stretchable cuff electrodes promise to tackle these challenges but often have limited performance and rely on unconventional materials. The aim of this study is to develop a high performance soft and stretchable cuff electrode based on inert materials for low-voltage nerve stimulation. Approach. We developed 50 mu m thick stretchable cuff electrodes based on silicone rubber, gold nanowire conductors and platinum coated nanowire electrodes. The electrode performance was characterized under strain cycling to assess the durability of the electrodes. The stimulation capability of the cuff electrodes was evaluated in an in vivo sciatic nerve rat model by measuring the electromyography response to various stimulation pulses. Main results. The stretchable cuff electrodes showed excellent stability for 50% strain cycling and one million stimulation pulses. Saturated homogeneous stimulation of the sciatic nerve was achieved at only 200 mV due to the excellent conformability of the electrodes, the low conductor resistance (0.3 Ohm sq(-1)), and the low electrode impedance. Significance. The developed stretchable cuff electrode combines favourable mechanical properties and good electrode performance with inert and stable materials, making it ideal for low power supply applications within bioelectronic medicine.
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| 37. |
- Linderhed, Ulrika, et al.
(författare)
-
Fully screen printed stretchable electrochromic displays
- 2021
-
Ingår i: Flexible and Printed Electronics. - : IOP Publishing Ltd. - 2058-8585. ; 6:4
-
Tidskriftsartikel (refereegranskat)abstract
- The advent of the Internet of Things and the growing interest in continuous monitoring by wearables have created a need for conformable and stretchable displays. Electrochromic displays (ECDs) are receiving attention as a cost-effective solution for many simple applications. However, stretchable ECDs have yet to be produced in a robust, large scale and cost-efficient manner. Here we develop a process for making fully screen printed stretchable ECDs. By evaluating commercially available inks with respect to electromechanical properties, including electrochromic PEDOT:PSS inks, our process can be directly applied in the manufacturing of stretchable organic electronic devices. The manufactured ECDs retained colour contrast with useful switching times at static strains up to 50% and strain cycling up to 30% strain. To further demonstrate the applicability of the technology, double-digit 7-segment ECDs were produced, which could conform to curved surfaces and be mounted onto stretchable fabrics while remaining fully functional. Based on their simplicity, robustness and processability, we believe that low cost printed stretchable ECDs can be easily scaled up and will find many applications within the rapidly growing markets of wearable electronics and the Internet of Things. © 2021 The Author(s).
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| 38. |
- Llerena Zambrano, Byron, et al.
(författare)
-
Soft Electronics Based on Stretchable and Conductive Nanocomposites for Biomedical Applications
- 2021
-
Ingår i: Advanced Healthcare Materials. - : WILEY. - 2192-2640 .- 2192-2659. ; 10:3
-
Tidskriftsartikel (refereegranskat)abstract
- Research on the field of implantable electronic devices that can be directly applied in the body with various functionalities is increasingly intensifying due to its great potential for various therapeutic applications. While conventional implantable electronics generally include rigid and hard conductive materials, their surrounding biological objects are soft and dynamic. The mechanical mismatch between implanted devices and biological environments induces damages in the body especially for long-term applications. Stretchable electronics with outstanding mechanical compliance with biological objects effectively improve such limitations of existing rigid implantable electronics. In this article, the recent progress of implantable soft electronics based on various conductive nanocomposites is systematically described. In particular, representative fabrication approaches of conductive and stretchable nanocomposites for implantable soft electronics and various in vivo applications of implantable soft electronics are focused on. To conclude, challenges and perspectives of current implantable soft electronics that should be considered for further advances are discussed.
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| 39. |
- Mardi, Saeed, et al.
(författare)
-
Interfacial Effect Boosts the Performance of All-Polymer Ionic Thermoelectric Supercapacitors
- 2022
-
Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 9:31
-
Tidskriftsartikel (refereegranskat)abstract
- Ionic thermoelectric supercapacitors (ITESCs) have recently been developed for converting low-grade waste heat into electricity. Until now, most reports of ITESCs have been focused on the development of electrolytes, which then have been combined with a specific electrode material. Here, it is demonstrated that the electrode is not only critical for electrical energy storage but also greatly affects the effective thermopower (S-eff) of an ITESC. It is shown that the same ion gel can generate a positive thermopower in an ITESC when using gold nanowire (AuNW) electrodes, while generating a negative thermopower when using poly(3,4-ethylendioxythiophene):polystyrene sulfonate (PEDOT:PSS) electrodes. The achieved negative sign of the S-eff could be attributed to the Donnan exclusive effect from the polyanions in the PEDOT:PSS electrodes. After examining the thermovoltage, capacitance and charge retention performance of the two ITESCs, it is concluded that PEDOT:PSS is superior to AuNWs as electrodes. Moreover, a new strategy of constructing an ionic thermopile of multiple p- and n-type legs is achieved by series-connecting these legs with same electrolyte but different electrodes. Using interfacial effect at ionic gels/PEDOT:PSS electrode interface, an enhanced thermoelectric effect in ITESCs is obtained, which constitutes one more step towards efficient, low-cost, flexible, and printable ionic thermoelectric modules for energy harvesting.
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| 40. |
- Mardi, Saeed, et al.
(författare)
-
The Interfacial Effect on the Open Circuit Voltage of Ionic Thermoelectric Devices with Conducting Polymer Electrodes
- 2021
-
Ingår i: Advanced Electronic Materials. - : Wiley. - 2199-160X. ; 7:12
-
Tidskriftsartikel (refereegranskat)abstract
- Organic-based energy harvesting devices can contribute to a sustainable solution for the transition to renewable energy sources. The concept of ionic thermoelectrics (iTE) has been recently proposed and motivated by the high values of thermo-voltage in electrolytes. So far, most research has focused on developing new electrolytes with high Seebeck coefficient. Despite the major role of the electrode materials in supercapacitors and batteries, the effect of various electrodes on energy harvesting in iTE devices has not been widely studied. In this work, the conducting polymer poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is investigated as the functional electrodes in iTE supercapacitors. Through investigating the thermo-voltage of iTEs of the same electrolyte with varying composition of PEDOT electrodes, it is identified that the different PSS content greatly affects the overall thermo-induced voltage coefficient, S-eff (i.e., effective thermopower). The permselective polyanion in the electrode causes cation concentration differences at the electrode/electrolyte interface and contributes to an interfacial potential drop that is temperature dependent. As a result, the overall thermo-voltage of the device possesses both an interfacial and a bulk contribution. The findings extend the fundamental understanding of iTE effect with functional electrodes, which could lead a new direction to enhance the heat-to-electricity conversion.
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| 41. |
- Modarresi, Mohsen, et al.
(författare)
-
Microscopic Understanding of the Granular Structure and the Swelling of PEDOT:PSS
- 2020
-
Ingår i: Macromolecules. - : AMER CHEMICAL SOC. - 0024-9297 .- 1520-5835. ; 53:15, s. 6267-6278
-
Tidskriftsartikel (refereegranskat)abstract
- The conjugated polymer poly(3,4-ethylenedioxythiophene) polymerized and stabilized in the presence of polystyrenesulfonate (best known as PEDOT:PSS) is a working horse of organic electronics and bioelectronics and one of the most important conductive polymers. While its morphology is complex and depends on the details in synthesis and post-treatment, its distinctive and common feature is a two-phase granular structure attributed to PEDOT- and PSS-rich regions. Yet, there is still no well-established consensus concerning the precise nature of PEDOT- and PSS-rich regions as well as their chemical composition and structure. In this study we perform coarse-grained MARTINI molecular dynamics simulations of PEDOT:PSS focusing on understanding its two-phase morphology as well as water intake and ion exchange. We demonstrate that PEDOT:PSS is an essentially three-component system consisting of positively charged PEDOT chains, PSS chains with mostly deprotonated sulfonate groups, and protonated PSS chains. PEDOT-rich regions are predominantly composed of PEDOT and deprotonated PSS chains, whereas PSS-rich regions are composed of protonated PSS chains. Our calculations unravel how PEDOT-and PSS-rich regions are formed from the solution phase during the drying process. We show that when the dry polymer film is immersed in water, its swells by nearly 60%, and we demonstrate that the origin of swelling is related to deprotonation of the sulfonate groups in the PSS-rich regions. It is mostly PSS-rich regions that swell while the PEDOT-rich regions remain rather unchanged. We demonstrate that swelling of the film is rather insignificant during reduction/oxidation within the cyclic voltammetry (CV) conditions. We show that during CV experiments each counterion brings on overage approximate to 4 water molecules into the polymer region. Our simulations of swelling, CV experiments, and pi-pi stacking formation in PEDOT and PSS match well the experimental results. Our theoretical studies unravel the most important morphological aspects of one of the most important polymers for organic electronics, providing the essential insight needed for the material and device design and improvements.
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| 42. |
- Mohammadi, Mohsen, 1992-
(författare)
-
Stretchable electronics using wood-based functional materials
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stretchable electronics allows for direct integration into deforming systems like clothing, skin, and tissue, thereby enabling novel applications in soft robotics, wearable electronics, health monitoring, therapeutics, and human-machine interfaces. However, achieving seamless integration with the human body poses significant challenges, necessitating the development of functional materials with a low Young’s modulus matching biological tissues to avoid any discomfort or immune response. Additionally, as electronic devices are becoming increasingly used in different settings, accumulation of electronic waste, and the utilization of unsustainable raw materials are emerging as pressing environmental challenges. Therefore, it is important that the design and fabrication of these devices consider not only high performance, but also its environmental sustainability. Therefore the focus of this thesis is on enhancing the performance and sustainability aspects of stretchable electronics through using renewable wood-based functional wood-based materials in 4 papers. Paper I focuses on the development of versatile soft electromagnetic actuators for soft robotic applications. These stretchable electromagnetic actuators were capable of contraction, expansion, hopping, and locomotion without the need for external magnetic fields. By embedding strain sensors made of conductive cellulose nanofibril (CNF)-based foam, the actuators could internally monitor their states, enhancing their controllability and autonomy. In Paper II, a soft haptic system was designed to stimulate the sense of touch. The haptic system was based on a soft electromagnetic actuator concept that included a soft magnet and stretchable conducting composite consisting of silver flakes and a styrene elastomer. The system demonstrated an improved tactile response enabled by vibration amplitude sensing through conductive CNF-based foams. This novel design offers potential applications in human–machine interfaces and virtual reality tools. Paper III presents a scalable approach for the fabrication of ultra-soft high-resolution multilayer stretchable printed circuit boards (sPCBs). A wood derived biopolymer, lignin, was used to develop a water processable sacrificial mask bio-composite for laser-patterning of high-resolution prints of ultra-soft and stretchable conductors with high-aspect-ratio structures. Additionally, this method enabled the stable integration of rigid components onto the sPCBs that can facilitate their use for miniaturized electronic devices. Lastly, paper IV introduces a fluid-based electrode concept for stretchable batteries using the biopolymer lignin. Fluidity is engineered into the cathode and anode, thereby decoupling the mechanical and electrochemical properties of the battery electrodes, allowing for high deformability without sacrificing capacity. The developed wood-based fluid stretchable battery could potentially be used as a sustainable energy storage component to power wearable devices. Overall, the thesis has contributed to the advancement of the field of stretchable electronics. It provided valuable insights into the potential utilization of wood-based functional materials into a variety of devices, fabrication methods, and design concepts in stretchable electronics, incorporating both high performance and environmental sustainability. The knowledge generated from this thesis can be used as a prospective guideline to design next-generation stretchable electronics devices.
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| 43. |
- Mohammadi, Mohsen, et al.
(författare)
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Versatile Ultrasoft Electromagnetic Actuators with Integrated Strain-Sensing Cellulose Nanofibril Foams
- 2023
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Ingår i: ADVANCED INTELLIGENT SYSTEMS. - : WILEY. - 2640-4567. ; 5:7
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Tidskriftsartikel (refereegranskat)abstract
- As robots more frequently fraternize with humans in everyday life, aspects such as safety, flexibility of tasks, and appearance become increasingly important. Soft robotics is attractive for new human-close applications, but soft actuators constitute a major challenge both in terms of actuation force and speed, and in terms of control and accuracy of the deformable soft actuator body. Herein, several of these challenges are addressed by developing versatile ultrasoft electromagnetic actuators that operate in absence of external magnetic fields, while simultaneously monitoring their states by internal strain sensors. The versatile actuators can compress to less than 50% of their initial length with strain-independent contraction force and operate in both contraction and expansion modes up to 200 Hz frequency while conforming to curved surfaces. The soft multilayer conductive cellulose-based foams are lightweight (3 mg cm(-3)) and provide internal strain-sensing capability and structural support, thereby improving the monitoring and controllability of the actuators while maintaining an axial softness of 0.6 kPa. It is believed that the concept of soft versatile electromagnetic actuators with integrated lightweight strain-sensing foams is promising for a wide range of applications within soft robotics.
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| 44. |
- Oikonomou, Vasileios, et al.
(författare)
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Elucidating the Bulk Morphology of Cellulose-Based Conducting Aerogels with X-Ray Microtomography
- 2023
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Ingår i: Advanced Materials Technologies. - : WILEY. - 2365-709X. ; 8:23
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Tidskriftsartikel (refereegranskat)abstract
- Conducting cellulose composites are promising sustainable functional materials that have found application in energy devices, sensing and water purification. Herein, conducting aerogels are fabricated based on nanofibrillated cellulose and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, using the ice templating technique, and their bulk morphology is characterized with X-ray microtomography. The freezing method (−20 °C in a freezer vs liquid nitrogen) does not impact the mean porosity of the aerogels but the liquid-N2 aerogels have smaller pores. The integration of carbon fibers as addressing electrodes prior to freezing results in increased mean porosity and pore size in the liquid-N2 aerogels signifying that the carbon fibers alter the morphology of the aerogels when the freezing is fast. Spatially resolved porosity and pore size distributions also reveal that the liquid-N2 aerogels are more inhomogeneous. Independent of the freezing method, the aerogels have similar electrochemical properties. For aerogels without carbon fibers, freezer-aerogels have higher compression modulus and are less stable under cycling compression fatigue test. This can be explained by higher porosity with larger pores in the center of liquid-N2 aerogels and thinner pore walls. This work demonstrates that micro-CT is a powerful tool for characterizing the morphology of aerogels in a non-destructive and spatially resolved manner.
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| 45. |
- Oladiran Bamgbopa, Musbadeen, et al.
(författare)
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Modelling of heterogeneous ion transport in conducting polymer supercapacitors
- 2021
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 9:4, s. 2184-2194
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Tidskriftsartikel (refereegranskat)abstract
- The ongoing electrification of many energy systems has created a large demand for low-cost and scalable electrical energy storage solutions. Conducting polymer supercapacitors have received significant attention for this purpose due to the abundance of their constituent materials. Although there exists a large body of experimental work on conducting polymer supercapacitors, a detailed understanding of the mixed electronic-ionic transport processes within these devices and the included materials, is still lacking. Modelling, in combination with experimental data, is a powerful tool to facilitate a detailed understanding of the transport processes within the materials and devices. However, to date, there has been a shortage of physical models which account for the non-ideal capacitances typically found in conducting polymer-based supercapacitors. Here, we report a novel model which reproduces experimental data and provides insights into the cyclic voltammograms, galvanostatic charge-discharge curves, self-discharge characteristics, and impedance spectroscopy results of supercapacitors based on the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and cellulose nanofibrils. We find that the non-ideal capacitive characteristics of the supercapacitors can be reproduced by the incorporation of heterogeneous ion transport features within the electrodes, comprising low ion diffusivity regions. The difference in charging rates of the high and low ion diffusivity regions accounts for the experimentally observed trends in cyclic voltammograms and self-discharge characteristics. The developed model demonstrates how complex transport processes, which govern the specifications of organic energy devices, can be analysed beyond the scope of conventional equivalent circuit models. It also provides an insight into how various transport and polarization processes are manifested in real measurement data and thus defines the limiting processes of conducting polymer energy storage devices.
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| 46. |
- Oladiran Bamgbopa, Musbadeen, et al.
(författare)
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Understanding the characteristics of conducting polymer-redox biopolymer supercapacitors
- 2019
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 7:41, s. 23973-23980
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Tidskriftsartikel (refereegranskat)abstract
- The growth of renewable energy production has sparked a huge demand for cheap and large-scale electrical storage solutions. Organic supercapacitors and batteries are envisioned as one, among several, candidates for this task due to the great abundance of their constituent materials. In particular, the class of supercapacitors based on conjugated polymer-redox biopolymer composites are of great interest, since they combine the benefit of high electrical conductivity of the conducting polymers with the low cost and high specific capacitance of redox biopolymers. The optimization of such complex systems is a grand challenge and until now there have been a lack of models available to ease that task. Here, we present a novel model that combines the charge transport and impedance properties of conducting polymers with the electrochemical characteristics of redox polymers. The model reproduces a wide range of experimental data and elucidates the coupling of several critical processes within these supercapacitors, such as the double-layer capacitance, redox kinetics and dissolution/release of the redox polymer to the electrolyte. Further, the model also predicts the dependencies of the power and energy densities on the electrode composition. The developed model shows how organic supercapacitors can be analyzed beyond archetypical equivalent circuit models and thus constitutes a promising tool for further advancements and optimization within the field of research of green energy storage technology.
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| 47. |
- Park, Taehyun, et al.
(författare)
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Ionoelastomer electrolytes for stretchable ionic thermoelectric supercapacitors
- 2023
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Ingår i: Nano Energy. - : ELSEVIER. - 2211-2855 .- 2211-3282. ; 114
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Tidskriftsartikel (refereegranskat)abstract
- Ionic thermoelectric supercapacitors (ITESCs) produce orders of magnitude higher voltages than those of con-ventional thermoelectrics (TEs) based on the thermo-diffusion of electrons/holes and are therefore attractive for converting low-grade heat into electricity. The stretchability and stability of the whole ITESC are important for wearable heat harvesting applications. Recent studies on ITESC have focused on stretchable ionic TE electrolytes with a giant Seebeck coefficient, but there are no reports of fully stretchable ITESCs for wearable heat harvesting devices due to the lack of stretchable electrodes and stretchable ionic TE electrolytes with stability. Herein, we present a fully stretchable ITESC composed of stable high-performance ionic thermoelectric elastomer (ITE) electrolyte and stretchable gold nanowire (AuNW) electrodes. The ITE shows excellent air stability (> 60 d) in comparison to hydrogel-based electrolytes that are susceptible to dehydration in ambient conditions. Further-more, the ITE exhibits an apparent thermopower up to 38.9 mV K-1 and ionic conductivity of 3.76 x 10-1 mS cm-1, which both are maintained up to a tensile strain of 250%. Finally, a fully stretchable ITESC with AuNW electrodes is developed which can harvest energy from thermal gradients during deformations.
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| 48. |
- Paulsen, B.D., et al.
(författare)
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Organic mixed ionic–electronic conductors
- 2020
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Ingår i: Nature Materials. - : Nature Publishing Group. - 1476-1122 .- 1476-4660. ; 19, s. 13-26
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Forskningsöversikt (refereegranskat)abstract
- Materials that efficiently transport and couple ionic and electronic charge are key to advancing a host of technological developments for next-generation bioelectronic, optoelectronic and energy storage devices. Here we highlight key progress in the design and study of organic mixed ionic–electronic conductors (OMIECs), a diverse family of soft synthetically tunable mixed conductors. Across applications, the same interrelated fundamental physical processes dictate OMIEC properties and determine device performance. Owing to ionic and electronic interactions and coupled transport properties, OMIECs demand special understanding beyond knowledge derived from the study of organic thin films and membranes meant to support either electronic or ionic processes only. We address seemingly conflicting views and terminology regarding charging processes in these materials, and highlight recent approaches that extend fundamental understanding and contribute to the advancement of materials. Further progress is predicated on multimodal and multi-scale approaches to overcome lingering barriers to OMIEC design and implementation.
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| 49. |
- Persson, Kristin M, et al.
(författare)
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Selective Detachment of Human Primary Keratinocytes and Fibroblasts Using an Addressable Conjugated Polymer Matrix
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Conjugated polymers have been used in several applications for electronic control of cell cultures over the last years. We have shown detachment of human endothelial cells using a thin film of a self-doped water-soluble conjugated polymer. Upon electrochemical oxidation, the film swells, cracks and finally detaches taking cells cultured on top along with it. The polymer can be patterned using standard photolithography. The detachment only occurs above a threshold potential of +0.7 V and this fact has been used to create a simple actively addressed matrix, based on a resistor network placed in an encapsulated back plane. The matrix has individually detachable pixels. In this paper we have evaluated detachment of human primary keratinocytes and fibroblasts using PEDOT-S:H. In addition, we have studied effects of serum proteins, added as nutrients to the cell culture medium, on the detachment properties. It was found that at prolonged incubation times protein adhesion effectively stopped the detachment. Using shorter incubation times before detachment, both keratinocytes and fibroblasts can be detached using a regular planar device as well as the matrix device for selective detachment. Spatial control of detachment could be of use when selecting cells for clonal expansion and in order to obtain a homogeneous starting population of cells aimed for tissue engineering purposes.
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| 50. |
- Persson, Kristin, et al.
(författare)
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Matrix Addressing of an Electronic Surface Switch Based on a Conjugated Polyelectrolyte for Cell Sorting
- 2015
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlag. - 1616-301X .- 1616-3028. ; 25:45, s. 7056-7063
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Tidskriftsartikel (refereegranskat)abstract
- Spatial control of cell detachment is potentially of great interest when selecting cells for clonal expansion and in order to obtain a homogeneous starting population of cells aimed for tissue engineering purposes. Here, selective detachment and cell sorting of human primary keratinocytes and fibroblasts is achieved using thin films of a conjugated polymer. Upon electrochemical oxidation, the polymer film swells, cracks, and finally detaches taking cells cultured on top along with it. The polymer can be patterned using standard photolithography to fabricate a cross-point matrix with polymer pixels that can be individually addressed and thus detached. Detachment occurs above a well-defined threshold of +0.7 V versus Ag/AgCl, allowing the use of a relatively simple and easily manufactured passive matrix-addressing configuration, based on a resistor network, to control the cell-sorting device. Selective and electronically controlled cell detachment is achieved using a conjugated polymer that detaches when electrochemically oxidized. The polymer is patterned to create a matrix with individually addressable pixels. The addressing is based on passive matrix addressing and is controlled by a resistance network. Human skin cells are cultured on the matrix, show good viability, and can be selectively detached.
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