| 11. |
- Say, Mehmet Girayhan, 1992-
(författare)
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Hybrid Materials for Wearable Electronics and Electrochemical Systems
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Flexible electronic systems such as wearable devices, sensors and electronic skin require power sources and sensing units that are mechanically robust, operational at low bending radius, and environmentally friendly. Recently, there has been an enormous interest in active materials such as thin film semiconductors, conductive polymers, and ion-electron conductors. These materials can be deposited with both printing and microfabrication techniques onto the flexible substrates such as plastics and paper. In addition, paper-based composites with nanofibrillated cellulose are favorable due to their mechanical strength, porosity, and solution-processability. Printing of such systems enables mass-production of large area electrochemical devices i.e., batteries, supercapacitors and fuel cells. Moreover, designing ultrathin devices for such concepts are promising for implantable and skin-like conformable electronics.The aim of this thesis is the development of flexible electronic devices where, both organic and inorganic materials are explored, and examples of smart packaging and wearable electronics are demonstrated. Within the thesis, two different fabrication approaches are presented to achieve flexible electronics: (1) fabrication of porous paper electrodes for printable, wearable supercapacitor applications, where our efforts towards sustainable solutions for energy storage and (2) development of ultraflexible devices for electronic skin and implantable electronics to attain miniaturized, ultrathin device concepts. Overall, high performance electronic devices and demonstrators shown here have a significant impact on portable hybrid systems and flexible electronics applications.
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| 12. |
- Seitanidou, Maria, 1985-
(författare)
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Overcoming Limitations of Iontronic Delivery Devices
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organic electronic devices are considered as one of the best candidates to replace conventional inorganic electronic devices due to their electronic conductive functionality, low-cost production techniques, the ability to tune their optical and electronic properties using organic chemistry, and their mechanical flexibility. Moreover, these systems are ideal for bioelectronic applications due to their softness, biocompatibility, and most importantly, their electronic and ionic transport. Indeed, these materials are compatible with biological tissues and cells improving the signal transduction between electronic devices and electrically excitable cells. As ions serve as one of the primary signal carriers of cells, they can selectively tune a cell’s activity; therefore, an improved interface between electronics and biological systems can offer several advantages in healthcare, e.g. the development of efficient drug delivery devices. The main focus of this thesis is the development of electronic delivery devices. Electrophoretic delivery devices called organic electronic ion pumps (OEIPs) are used to electronically control the delivery of small ions, neurotransmitters, and drugs with high spatiotemporal resolution. This work elucidates the ion transport processes and phenomena that happen in the ion exchange membranes during ion delivery and clarifies which parameters are crucial for the ion transport efficiency of the OEIPs. This thesis shows a systematic investigation of these parameters and indicates new methods and OEIP designs to overcome these challenges. Two novel OEIP designs are developed and introduced in this thesis to improve the local ion transport while limiting side effects. OEIPs based on palladium proton trap contacts can improve the membrane permselectivity and optimize the delivery of γ-aminobutyric acid (GABA) neurotransmitters at low pH while preventing any undesired pH changes from proton transport in the biological systems. And OEIPs based on glass capillary fibers are developed to overcome the limitations of devices on planar substrates, related to more complex and larger biologically relevant ion delivery with low mobility for implantable applications. This design can optimize the transport of ions and drugs such as salicylic acid (SA) at low concentrations and at relatively much higher rates, thereby addressing a wider range of biomedically relevant applications and needs.
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| 13. |
- Tran, Van Chinh, 1990-
(författare)
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Wood Templated Organic Electronics
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In today’s digital era, electronics are integral to most activities in our daily lives, offering swift and global communication, powerful data processing tools, and advanced sensor devices. However, there are drawbacks to the exponentially growing demand for electronics, such as the depletion of fossil resources, and the complexities surrounding recycling electronic waste (E-waste). As we gradually step into the era of sustainability, it is necessary to explore alternative resources and develop greener electronic technologies. For this purpose, organic electronics (OE) has emerged as an interesting alternative, owning to its potential for low-energy fabrication and use of organic materials composed of Earth-abundant elements.The term "organic electronics" has been used widely to refer to electrical devices crafted from organic materials, typically semiconducting polymers (sCPs). This arises from the fact that most developed OE devices such as solar cells, transistors, supercapacitors, and batteries are centered around such materials. Along with the development of different semiconducting polymer varieties, materials from various natural resources have also been explored for devices’ electrodes, binders, and electrolytes. Among them, materials from the forest have emerged as abundant, renewable, and valuable options. For many years, wood has been tailored and utilized as a device template, while its components including cellulose fibrils and lignin have been widely used as structural or active components in OE. Lignin has now become an important electrode and electrolyte active material in energy storage devices.This thesis presents new approaches and findings in the utilization of wood and lignin as active components in different OE applications. The thesis centers around two primary themes, in which the first involves the development and utilization of conductive wood (CW), containing lignin, and lignin nanoparticles (LNPs) for supercapacitors and battery applications. The second theme focuses on developing and employing conductive wood as an active electrode in the creation of a wood electrochemical transistor. Within the first theme, I have uncovered the potential of storing electricity in wood utilizing its redox-active component, native lignin. The discovery is reinforced by the successful employment of LNPs as active materials in an organic battery. Within the second theme, I have demonstrated the world's first wooden transistor, characterized its electronic performance, and discussed the pretreatment procedure of the wood substrate that is necessary for achieving a working device. This thesis is anticipated to contribute to new and valuable knowledge for encouraging the development of low-cost and sustainable OE in the future.
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| 14. |
- Wu, Zhixing, 1990-, et al.
(författare)
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Conducting Polymer‐Based e‐Refinery for Sustainable Hydrogen Peroxide Production
- 2023
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Ingår i: Energy & Environmental Materials. - : Wiley-Blackwell. - 2575-0356.
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Tidskriftsartikel (refereegranskat)abstract
- Electrocatalysis enables the industrial transition to sustainable production of chemicals using abundant precursors and electricity from renewable sources. De-centralized production of hydrogen peroxide (H2O2) from water and oxygen of air is highly desirable for daily life and industry. We report an effective electrochemical refinery (e-refinery) for H2O2 by means of electrocatalysis-controlled comproportionation reaction (2(H)O + O -> 2(HO)), feeding pure water and oxygen only. Mesoporous nickel (II) oxide (NiO) was used as electrocatalyst for oxygen evolution reaction (OER), producing oxygen at the anode. Conducting polymer poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) drove the oxygen reduction reaction (ORR), forming H2O2 on the cathode. The reactions were evaluated in both half-cell and device configurations. The performance of the H2O2 e-refinery, assembled on anion-exchange solid electrolyte and fed with pure water, was limited by the unbalanced ionic transport. Optimization of the operation conditions allowed a conversion efficiency of 80%.
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| 15. |
- Yang, Hongli, 1992-
(författare)
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Ion Transport in Cross-linked Nanocellulose Membranes
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ion-selective membranes, which allow ions with a certain charge and/or size to pass through while blocking other ions, have attracted much attention due to their diverse applications and outstanding roles in overcoming problems related to energy. In addition to the performance, the financial cost and renewability of materials are equally significant in the development of these membranes. Commonly, ion-selective membranes are prepared from traditional synthetic polymers that have put a heavy burden on the environment. Therefore, exploring low-cost, environment-friendly materials as the substitution of traditional polymers for ion-selective membranes will be beneficial from a sustainable perspective.Nanocellulose is a promising candidate for the next generation of ionic membranes due to its unique chemical structure and suitable physical dimensions. Furthermore, it can be produced from cellulose, which is the most abundant biopolymer on earth. Nanocellulose has many hydroxyl groups that provide many possibilities to introduce ion-functionalized groups on the cellulose chain through chemical treatment and modification. In addition, the physical entanglement of cellulose nanofibrils can generate a nanoscale porous structure that improves the ion permselectivity of membranes and provides a strong network that enhances the toughness of membranes. Among the disadvantages of nanocellulose-based products is poor wet stability due to the swelling induced by their hydrophilicity. This problem can be effectively solved using covalent cross-linking.This thesis aims to develop nanocellulose-based ionic membranes with excellent ionic transport properties as well as good wet stability and to explore their potential applications. First, the nanocellulose membranes cross-linked by 1,2,3,4-butanetetracarboxylic acid (BTCA) were developed. The relationship between the amount of cross-linker and the membranes’ pore size, charge density, and ionic transport properties was demonstrated. Based on the above fundamental understanding of the membranes’ performance, especially ion conductivity, and selectivity, their performance was then investigated in two potential applications, including osmotic power generators and redox flow batteries. Finally, the original cross-linked membrane, which is negatively charged, was combined with a corresponding membrane with positive surface charges to obtain bipolar membranes, which can be used for rectification. The properties of these bipolar membranes were investigated, with the conclusion that they can be used as an ionic diode under certain conditions.
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| 16. |
- Zabihipour, Marzieh, 1985-
(författare)
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Organic Electrochemical Transistors for Printed Digital Circuits
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organic electronics enables cost-effective production of flexible electronic devices with high throughput and easy processing compared to the conventional electronics. Organic electronics, therefore, has the potential to realize various innovative applications on a large scale, for example, flexible displays, smart windows, solar cells, electronic skin and implantable medical devices.Many of the materials employed in the field of organic electronics can be processed from chemical solutions. This allows for making various types of inks and hence the possibility to use the traditional high-volume printing methods such as screen printing, inkjet printing and gravure printing for fabricating organic electronic devices on different surfaces. Screen printing has advantages over the other methods in terms of the range of ink viscosity, resolution, and controllable thickness of dry ink film.For various applications envisioned for an integration of printed organic electronics with other technology platforms, a prolonged lifetime and low power consumption are desired. This requires an optimized design of the electronic components and circuits so that they can operate at reduced voltages to guarantee both the long lifetime and the low power consumption. This thesis focuses on designing fully screen printed vertically stacked organic electrochemical transistors (OECTs) and OECT-based circuits operating at low supply voltages and at the same time delivering high gain and low power consumption with long lifetime. The OECTs and OECT-based circuits employ poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) as the organic polymer in their channel. The multi-layered OECTs have a small footprint with a high manufacturing yield and performance uniformity across the printed area, making them suitable for complex printed circuits. Furthermore, various inverter designs based on the reliable and reproducible OECTs are developed and explored to target circuits that can perform at relatively low supply voltages, yet offering improved performance.
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| 17. |
- Zhang, Silan, 1992-
(författare)
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Organic Electrochemical Transistors : Materials and Challenges
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of organic mixed ionic-electronic conductors (OMIECs) has demonstrated the potential to transform the field of bioelectronics, spanning from medical diagnostics to neuromorphic computing hardware. To keep up with the fast-paced demands, it is crucial to develop customizable device fabrication, design new materials, improve operation stability, and explore the ion-electron interactions within OMIECs. This thesis explores the application of OMIECs in organic electrochemical transistors (OECTs), a crucial component of a range of organic bioelectronic devices. To meet applications requiring rapid design iterations and leveraging digitally enabled direct-write techniques, we developed a novel approach for fabricating fully 3D-printed OECTs using a direct-write additive process. This method involves utilizing 3D printable inks with conductive, semiconductive, insulating, and electrolyte properties. The resulting fully 3D-printed OECTs operate in the depletion mode and can be produced on flexible substrates, ensuring excellent mechanical durability and resilience in various environmental conditions. These 3D-printed OECTs exhibit impressive dopamine biosensing capabilities, detecting concentrations as low as 6 µM without the need for metal gate electrodes. Furthermore, they demonstrate long-term memory response lasting up to approximately 1 hour, highlighting their potential for diverse applications such as sensors and neuromorphic hardware. We have addressed the issue of sluggish response times in printed OECTs by utilizing multi-walled carbon nanotubes (MWCNTs) and the π-conjugated redox polymer called poly(benzimidazobenzo-phenanthroline) (BBL) to create high-performing n-type OECTs. By incorporating MWCNTs, we were able to improve the electron mobility of the transistors by more than 10 times, resulting in a rapid response time of just 15 ms and a high μC* value (which is the product of electron mobility and volumetric capacitance) of approximately 1 F cm–1 V−1 s−1. These breakthroughs have allowed us to develop complementary inverters that have a voltage gain of over 16, a significant worst-case noise margin at a supply voltage lower than 0.6 V and consume less than 1 µW of power. However, the operational stability of complementary inverters is hindered by the degradation of p-type OMIECs. The oxygen reduction reaction (ORR) is a common electrochemical side reaction that poses challenges to the stability of OECTs, but the underlying connection between ORR and material degradation remains poorly understood. In our investigation, we examined the influence of ORR on the stability and degradation mechanisms of thiophene-based OECTs. Our findings reveal that the polymer backbone experiences degradation as a result of the pH increase during ORR. To address this issue, we introduced a protective polymer glue layer between the semiconductor channel and the aqueous electrolyte, effectively suppressing the occurrence of ORR and significantly enhancing the stability of the OECTs. This improvement is evident in the nearly 90% retention of current during ≈2 hours of cycling in the saturation regime. Finally, we investigated the ionic-electronic transport properties in BBL-based OECTs using various electrolytes. We found that the peak drain current is achieved at a doping level of 1 electron per repeating unit, decreasing thereafter. The interaction between ions and the polymer reduces the voltage needed for this level of doping but also lowers the peak drain current. Unlike thiophene-based OECTs, larger cation sizes don't improve BBL-based OECT performance. Additionally, Lewis acids adversely affect BBL's electrical properties due to their impact on the polymer microstructure. We hope these studies will inspire our peers in the field of materials synthesis, device processing, and scalable digital techniques, paving the way for next-generation, reliable, and safe bioelectronics.
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| 18. |
- Ajjan, Fátima, 1986-, et al.
(författare)
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Doped Conjugated Polymer Enclosing a Redox Polymer : Wiring Polyquinones with Poly(3,4‐Ethylenedioxythiophene)
- 2020
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Ingår i: Advanced Energy and Sustainability Research. - : John Wiley & Sons. - 2699-9412. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- The mass implementation of renewable energies is limited by the absence of efficient and affordable technology to store electrical energy. Thus, the development of new materials is needed to improve the performance of actual devices such as batteries or supercapacitors. Herein, the facile consecutive chemically oxidative polymerization of poly(1-amino-5-chloroanthraquinone) (PACA) and poly(3,4-ethylenedioxythiophene (PEDOT) resulting in a water dispersible material PACA-PEDOT is shown. The water-based slurry made of PACA-PEDOT nanoparticles can be processed as film coated in ambient atmosphere, a critical feature for scaling up the electrode manufacturing. The novel redox polymer electrode is a nanocomposite that withstands rapid charging (16 A g−1) and delivers high power (5000 W kg−1). At lower current density its storage capacity is high (198 mAh g−1) and displays improved cycling stability (60% after 5000 cycles). Its great electrochemical performance results from the combination of the redox reversibility of the quinone groups in PACA that allows a high amount of charge storage via Faradaic reactions and the high electronic conductivity of PEDOT to access to the redox-active sites. These promising results demonstrate the potential of PACA-PEDOT to make easily organic electrodes from a water-coating process, without toxic metals, and operating in non-flammable aqueous electrolyte for large scale pseudocapacitors.
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| 19. |
- Che, Canyan, 1988-, et al.
(författare)
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Twinning Lignosulfonate with a Conducting Polymer via Counter-Ion Exchange for Large-Scale Electrical Storage
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley-VCH Verlag. - 2366-7486. ; 3:9
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Tidskriftsartikel (refereegranskat)abstract
- Lignosulfonate (LS) is a large-scale surplus product of the forest and paper industries, and has primarily been utilized as a low-cost plasticizer in making concrete for the construction industry. LS is an anionic redox-active polyelectrolyte and is a promising candidate to boost the charge capacity of the positive electrode (positrode) in redox-supercapacitors. Here, the physical-chemical investigation of how this biopolymer incorporates into the conducting polymer PEDOT matrix, of the positrode, by means of counter-ion exchange is reported. Upon successful incorporation, an optimal access to redox moieties is achieved, which provides a 63% increase of the resulting stored electrical charge by reversible redox interconversion. The effects of pH, ionic strength, and concentrations, of included components, on the polymer–polymer interactions are optimized to exploit the biopolymer-associated redox currents. Further, the explored LS-conducting polymer incorporation strategy, via aqueous synthesis, is evaluated in an up-scaling effort toward large-scale electrical energy storage technology. By using an up-scaled production protocol, integration of the biopolymer within the conducting polymer matrix by counter-ion exchange is confirmed and the PEDOT-LS synthesized through optimized strategy reaches an improved charge capacity of 44.6 mAh g−1.
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| 20. |
- Diacci, Chiara, 1992-
(författare)
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Organic Bioelectronic Devices for Selective Biomarker Sensing : Towards Integration with Living Systems
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inorganic materials have been the main players of the semiconductor industry for the past forty years. However, there has been a continuous interest and growth in the research and in the application of organic semiconductors (OSCs) as active materials in electronic devices, due to the possibility to process these materials at low temperature on flexible substrates, fabricate them on large-area, and upscale their fabrication using cost-effective strategies such as printing. Because of these features, organic electronic devices are rapidly emerging as biosensors for biomarkers, with a high potential for becoming a high-throughput tool even deployable at the point-of-care. One of the most used and studied platforms is the organic electrochemical transistor (OECT). OECTs have been largely used as biosensors in order to transduce and amplify electrical signals or detect biological analytes upon proper functionalization with specific biorecognition units. OECTs can operate at low voltages, are easy to fabricate on different substrates, and are compatible with the aqueous environment, and can therefore be interfaced with living systems, ranging from mammals to plants. The OECT device configuration includes a gate electrode that modulates the current in the channel through an electrolyte, which can be not only a buffered solution but even a complex biological fluid. When OECTs are operated as biosensors, the sensing mechanism relies on the current variation generated from specific reactions with the analyte of interest. These devices are paving the way to the development of point-of-care technologies and portable biosensors with fast and label-free detection. Moreover, OECTs can help to reveal new biological insight and allow a better understanding of physiological processes. During my PhD, I focused on design, fabrication, and validation of different OECT-based biosensors for the detection of biomarkers that are relevant for healthcare applications, thus showing their high potential as a proper sensing platform. We developed sensors towards different analytes, ranging from small molecules to proteins, with ad hoc designed materials strategies to endow the device with selectivity towards the species of interest. Most notably, I also demonstrated the possibility of integrating OECTs in plants, as an example of interfacing these biosensors with living systems. In the first two papers, we developed screen printed OECTs, presenting PEDOT:PSS as the semiconducting material on the channel. In the first case, the device also featured a PEDOT:PSS gate electrode which was further functionalized with biocompatible gelatin and the enzyme urease to ensure selectivity toward the analyte of interest, namely urea. The biosensor was able to monitor increasing urea concentrations with a limit of detection of 1 µM. In the second paper the screen-printed carbon gate electrode was first modified with platinum and then we ensured selectivity towards the analyte uric acid, a relevant biomarker for wound infection, by entrapping urate oxidase in a dual-ionic-layer hydrogel membrane to filter out charged interfering agents. The biosensor exhibited a 4.5 µM limit of detection and selectivity even in artificial wound exudate. In the third paper we designed an interleukin-6 (IL6) OECT based biosensor able to detect the cytokine down to the pM regime in PBS buffer. The mechanism of detection relied on the specific binding between an aptamer, used as sensing unit on the gate electrode, and the IL6 in solution, allowing for detection ranging from physiological to pathological levels. In the last two papers we developed OECT based biosensors to be interfaced with the plant world. In the fourth paper we presented a glucose sensor, based on the enzyme glucose oxidase (GOx) to detect glucose export from chloroplasts. In particular, we demonstrated real-time glucose monitoring with temporal resolution of 1 minute in complex media. In the fifth paper, we developed implantable OECT-based sugar sensors for in vivo real-time monitoring of sugar transport in poplar trees. The biosensors presented a multienzyme-functionalized gate endowing the device with specificity towards glucose and sucrose. Most notably, the OECT sensors did not cause a significant wound response in the plant, allowing us to demonstrate that OECT-based sensors are attractive tools for studying transport kinetics in plants, in vivo and real-time.
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