| 1. |
- Abdullaeva, Oliya, et al.
(författare)
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Faradaic Pixels for Precise Hydrogen Peroxide Delivery to Control M-Type Voltage-Gated Potassium Channels
- 2022
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Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- H2O2 plays a significant role in a range of physiological processes where it performs vital tasks in redox signaling. The sensitivity of many biological pathways to H2O2 opens up a unique direction in the development of bioelectronics devices to control levels of reactive-oxygen species (ROS). Here a microfabricated ROS modulation device that relies on controlled faradaic reactions is presented. A concentric pixel arrangement of a peroxide-evolving cathode surrounded by an anode ring which decomposes the peroxide, resulting in localized peroxide delivery is reported. The conducting polymer (poly(3,4-ethylenedioxythiophene) (PEDOT), is exploited as the cathode. PEDOT selectively catalyzes the oxygen reduction reaction resulting in the production of hydrogen peroxide (H2O2). Using electrochemical and optical assays, combined with modeling, the performance of the devices is benchmarked. The concentric pixels generate tunable gradients of peroxide and oxygen concentrations. The faradaic devices are prototyped by modulating human H2O2-sensitive Kv7.2/7.3 (M-type) channels expressed in a single-cell model (Xenopus laevis oocytes). The Kv7 ion channel family is responsible for regulating neuronal excitability in the heart, brain, and smooth muscles, making it an ideal platform for faradaic ROS stimulation. The results demonstrate the potential of PEDOT to act as an H2O2 delivery system, paving the way to ROS-based organic bioelectronics.
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| 2. |
- Derek, Vedran, et al.
(författare)
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Micropatterning of organic electronic materials using a facile aqueous photolithographic process
- 2018
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Ingår i: AIP Advances. - : AMER INST PHYSICS. - 2158-3226. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- Patterning organic semiconductors via traditional solution-based microfabrication techniques is precluded by undesired interactions between processing solvents and the organic material. Herein we show how to avoid these problems easily and introduce a simple lift-off method to pattern organic semiconductors. Positive tone resist is deposited on the substrate, followed by conventional exposure and development. After deposition of the organic semiconductor layer, the remaining photoresist is subjected to a flood exposure, rendering it developable. Lift-off is then performed using the same aqueous developer as before. We find that the aqueous developers do not compromise the integrity of the organic layer or alter its electronic performance. We utilize this technique to pattern four different organic electronic materials: epindo-lidione (EPI), a luminescent semiconductor, p-n photovoltaic bilayers of metal-free phthalocyanine and N, N-dimethyltetracarboxylic diimide, and finally the archetypical conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). The result of our efforts is a facile method making use of well-established techniques that can be added to the toolbox of research and industrial scientists developing organic electronics technology. (c) 2018 Author(s).
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| 3. |
- Donahue, Mary, et al.
(författare)
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Wireless optoelectronic devices for vagus nerve stimulation in mice
- 2022
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Ingår i: Journal of Neural Engineering. - : IOP Publishing. - 1741-2560 .- 1741-2552. ; 19:6, s. 066031-
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Vagus nerve stimulation (VNS) is a promising approach for the treatment of a wide variety of debilitating conditions, including autoimmune diseases and intractable epilepsy. Much remains to be learned about the molecular mechanisms involved in vagus nerve regulation of organ function. Despite an abundance of well-characterized rodent models of common chronic diseases, currently available technologies are rarely suitable for the required long-term experiments in freely moving animals, particularly experimental mice. Due to challenging anatomical limitations, many relevant experiments require miniaturized, less invasive, and wireless devices for precise stimulation of the vagus nerve and other peripheral nerves of interest. Our objective is to outline possible solutions to this problem by using nongenetic light-based stimulation. Approach. We describe how to design and benchmark new microstimulation devices that are based on transcutaneous photovoltaic stimulation. The approach is to use wired multielectrode cuffs to test different stimulation patterns, and then build photovoltaic stimulators to generate the most optimal patterns. We validate stimulation through heart rate analysis. Main results. A range of different stimulation geometries are explored with large differences in performance. Two types of photovoltaic devices are fabricated to deliver stimulation: photocapacitors and photovoltaic flags. The former is simple and more compact, but has limited efficiency. The photovoltaic flag approach is more elaborate, but highly efficient. Both can be used for wireless actuation of the vagus nerve using light impulses. Significance. These approaches can enable studies in small animals that were previously challenging, such as long-term in vivo studies for mapping functional vagus nerve innervation. This new knowledge may have potential to support clinical translation of VNS for treatment of select inflammatory and neurologic diseases.
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| 4. |
- Gryszel, Maciej, et al.
(författare)
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Elevating Platinum to Volumetric Capacitance: High Surface Area Electrodes through Reactive Pt Sputtering
- 2024
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Ingår i: Advanced Healthcare Materials. - : WILEY. - 2192-2640 .- 2192-2659.
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Tidskriftsartikel (refereegranskat)abstract
- Platinum is the most widespread electrode material used for implantable biomedical and neuroelectronic devices, motivating exploring ways to improve its performance and understand its fundamental properties. Using reactive magnetron sputtering, PtOx is prepared, which upon partial reduction yields a porous thin-film form of platinum with favorable properties, notably record-low impedance values outcompeting other reports for platinum-based electrodes. It is established that its high electrochemical capacitance scales with thickness, in the way of volumetric capacitor materials like IrOx and poly(3,4-ethylenedioxythiophene), PEDOT. Unlike these two well-known analogs, however, it is found that PtOx capacitance is not caused by reversible pseudofaradaic reactions but rather due to high surface area. In contrast to IrOx, PtOx is not a reversible valence-change oxide, but rather a porous form of platinum. The findings show that this oxygen-containing form of Pt can place Pt electrodes on a level competitive with IrOx and PEDOT. Due to its relatively low cost and ease of preparation, PtOx can be a good choice for microfabricated bioelectronic devices. Platinum is used in many medical implants, but lags behind next-generation electrode materials in performance. How sputtered platinum oxide is a microfabricatable thin film material that provides bioelectronics electrodes with volumetric capacitance and low impedance that tweaks platinum to compete at the level of conducting polymers and IrOx is shown. image
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| 5. |
- Gryszel, Maciej, et al.
(författare)
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General Observation of Photocatalytic Oxygen Reduction to Hydrogen Peroxide by Organic Semiconductor Thin Films and Colloidal Crystals
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 10:16, s. 13253-13257
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Tidskriftsartikel (refereegranskat)abstract
- Low-cost semiconductor photocatalysts offer unique possibilities for industrial chemical transformations and energy conversion applications. We report that a range of organic semiconductors are capable of efficient photocatalytic oxygen reduction to H2O2 in aqueous conditions. These semiconductors, in the form of thin films, support a 2-electron/2-proton redox cycle involving photoreduction of dissolved O-2 to H2O2, with the concurrent photooxidation of organic substrates: formate, oxalate, and phenol. Photochemical oxygen reduction is observed in a pH range from 2 to 12. In cases where valence band energy of the semiconductor is energetically high, autoxidation competes with oxidation of the donors, and thus turnover numbers are low. Materials with deeper valence band energies afford higher stability and also oxidation of H2O to O-2. We found increased H2O2 evolution rate for surfactant-stabilized nanoparticles versus planar thin films. These results evidence that photochemical O-2 reduction may be a widespread feature of organic semiconductors, and open potential avenues for organic semiconductors for catalytic applications.
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| 6. |
- Gryszel, Maciej, et al.
(författare)
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High-Capacitance Nanoporous Noble Metal Thin Films via Reduction of Sputtered Metal Oxides
- 2022
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Ingår i: Advanced Materials Interfaces. - : WILEY. - 2196-7350. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Increasing the electrochemical surface area of noble metal electrodes is vital for many applications, including catalysis and bioelectronics. Herein, a method is presented for obtaining porous noble metal thin films via reactive magnetron sputtering of noble metal oxides, MOx, followed by their reduction using chemical reducers or electrochemical current. Variation of reduction conditions yields a range of different electrochemical and morphological properties. This method for obtaining porous noble metals is rapid, facile, and compatible with microfabrication processes. The resulting metallic films are porous and have competitively high capacitance and low impedance.
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| 7. |
- Hartmann, Florian, et al.
(författare)
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Scalable Microfabrication of Folded Parylene-Based Conductors for Stretchable Electronics
- 2021
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Ingår i: Advanced Electronic Materials. - : Wiley. - 2199-160X. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Electronics implemented on biocompatible ultrathin substrates like polyethylene terephthalate, polyimide, or parylene enabled a wide range of conformable, lightweight smart wearables and implantables. However, applications in such dynamic environments require robust devices that adjust and stretch while maintaining their functionality. Universal approaches that unite scalable, low-cost fabrication with high performance and versatile, space-efficient design are sparse. Here, stretchable architectures of parylene enabled by Origami-inspired folds at the micrometer scale are demonstrated. Parylene is directly deposited onto anisotropically etched silicon molds to greatly reduce bending stress, allowing folds with bending radii of a few micrometers. 50-nm-thick gold conductors fabricated on the folded parylene facilitate electronics with a stretchability of up to 55% tensile strain. The conductors sustain a resistance below 20 omega during reversible stretching of more than 10 000 cycles, enabling long-term operation in practical settings. This method presents a versatile tool for the microfabrication of stretchable devices with tunable properties.
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| 8. |
- Jakesova, Marie, et al.
(författare)
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Optoelectronic control of single cells using organic photocapacitors
- 2019
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Ingår i: Science Advances. - Washington, DC, United States : American Association for the Advancement of Science (A A A S). - 2375-2548. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- Optical control of the electrophysiology of single cells can be a powerful tool for biomedical research and technology. Here, we report organic electrolytic photocapacitors (OEPCs), devices that function as extracellular capacitive electrodes for stimulating cells. OEPCs consist of transparent conductor layers covered with a donor-acceptor bilayer of organic photoconductors. This device produces an open-circuit voltage in a physiological solution of 330 mV upon illumination using light in a tissue transparency window of 630 to 660 nm. We have performed electrophysiological recordings on Xenopus laevis oocytes, finding rapid (time constants, 50 mu s to 5 ms) photoinduced transient changes in the range of 20 to 110 mV. We measure photoinduced opening of potassium channels, conclusively proving that the OEPC effectively depolarizes the cell membrane. Our results demonstrate that the OEPC can be a versatile nongenetic technique for optical manipulation of electrophysiology and currently represents one of the simplest and most stable and efficient optical stimulation solutions.
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| 9. |
- Jakešová, Marie, 1991-
(författare)
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Wireless Bioelectronic Devices Driven by Deep Red Light
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of electronic devices in medical care is one of the main targets of precision medicine. The field of bioelectronic medicine uses electronic devices to diagnose or treat diseases and disorders in a complementary or alternative way to chemical drugs. It has been more than sixty years since the world’s first implantable battery-driven cardiac pacemaker was implanted here in Sweden. Since then, electronic therapies have been implemented for neurological disorders such as Parkinson’s disease, epilepsy, sensory and motor function restoration, and many more. However, electronics can also be used for delivery of conventional drugs in a more controlled, localized, and specific fashion.Therapeutic utility and patient comfort are maximized when the devices are as minimally invasive as possible. The most important milestone in the development of the cardiac stimulator was making it wireless. The early versions of the device required bulky parts to be placed outside of the body with transcutaneous electrical leads to the target site which led to high infection risk and frequent failures. To date, batteries remain the most common way to power implantable electronics. However, their large size and the necessity for replacement surgeries makes the technology relatively invasive. Alternative approaches to wireless power transfer are thus sought after. The most promising technologies are based on electromagnetic, ultrasound, or light-coupling methods. The aim of this thesis is to utilize tissue-penetrating deep red light for powering implantable devices. The overarching concept is an organic photovoltaic based on small molecule donor-acceptor bilayer junctions, which allows for ultrathin, flexible, minimally-invasive devices. Within this thesis, the photovoltaic device was utilized in two ways. Firstly, the photovoltaics are fabricated to act as an integrated driver for other implantable electronic components: 1) an organic electronic ion pump for acetylcholine delivery; 2) a depth-probe microelectrode stimulation device for epilepsy applications. Secondly, an alternative device, the organic electrolytic photocapacitor, is formed by replacing one of the solid electrodes by an electrolytic contact, thus yielding a minimalistic device acting as a direct photoelectrical stimulator. Within the thesis, the photocapacitive stimulation mechanism is validated by studying voltage-gated ion channels in a frog oocyte model. Next, two lithography-based patterning techniques are developed for fabricating these devices with better resolution and on flexible substrates suitable for in vivo operation. Finally, a chronic implant is demonstrated for in vivo sciatic nerve stimulation in rodents. The end result of this thesis is a series of novel device concepts and methods for stimulation of the nervous system using deep red light.
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| 10. |
- Jakešová, Marie, et al.
(författare)
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Wireless organic electronic ion pumps driven by photovoltaics
- 2019
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Ingår i: npj Flexible Electronics. - : Nature Publishing Group. - 2397-4621 .- 2397-4621. ; 3:1, s. 14-14
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Tidskriftsartikel (refereegranskat)abstract
- The organic electronic ion pump (OEIP) is an emerging bioelectronic technology for on-demand and local delivery of pharmacologically active species, especially targeting alkali ions, and neurotransmitters. While electrical control is advantageous for providing precise spatial, temporal, and quantitative delivery, traditionally, it necessitates wiring. This complicates implantation. Herein, we demonstrate integration of an OEIP with a photovoltaic driver on a flexible carrier, which can be addressed by red light within the tissue transparency window. Organic thin-film bilayer photovoltaic pixels are arranged in series and/or vertical tandem to provide the 2.5–4.5 V necessary for operating the high-resistance electrophoretic ion pumps. We demonstrate light-stimulated transport of cations, ranging in size from protons to acetylcholine. The device, laminated on top of the skin, can easily be driven with a red LED emitting through a 1.5-cm-thick finger. The end result of our work is a thin and flexible integrated wireless device platform.
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