| 1. |
- Brodsky, Jan, et al.
(författare)
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Downsizing the Channel Length of Vertical Organic Electrochemical Transistors
- 2023
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 15:22, s. 27002-27009
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Tidskriftsartikel (refereegranskat)abstract
- Organic electrochemical transistors (OECTs) are promisingbuildingblocks for bioelectronic devices such as sensors and neural interfaces.While the majority of OECTs use simple planar geometry, there is interestin exploring how these devices operate with much shorter channelson the submicron scale. Here, we show a practical route toward theminimization of the channel length of the transistor using traditionalphotolithography, enabling large-scale utilization. We describe thefabrication of such transistors using two types of conducting polymers.First, commercial solution-processed poly-(dioxyethylenethiophene):poly-(styrenesulfonate), PEDOT:PSS. Next, we also exploit the short channel lengthto support easy in situ electropolymerization of poly-(dioxyethylenethiophene):tetrabutylammonium hexafluorophosphate, PEDOT:PF6. Both variantsshow different promising features, leading the way in terms of transconductance(g (m)), with the measured peak g (m) up to 68 mS for relatively thin (280 nm) channel layerson devices with the channel length of 350 nm and with widths of 50,100, and 200 & mu;m. This result suggests that the use of electropolymerizedsemiconductors, which can be easily customized, is viable with verticalgeometry, as uniform and thin layers can be created. Spin-coated PEDOT:PSSlags behind with the lower values of g (m); however, it excels in terms of the speed of the device and alsohas a comparably lower off current (300 nA), leading to unusuallyhigh on/off ratio, with values up to 8.6 x 10(4). Ourapproach to vertical gap devices is simple, scalable, and can be extendedto other applications where small electrochemical channels are desired.
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| 2. |
- Gablech, Imrich, et al.
(författare)
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High-Conductivity Stoichiometric Titanium Nitride for Bioelectronics
- 2023
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Ingår i: Advanced Electronic Materials. - : WILEY. - 2199-160X. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Bioelectronic devices such as neural stimulation and recording devices require stable low-impedance electrode interfaces. Various forms of nitridated titanium are used in biointerface applications due to robustness and biological inertness. In this work, stoichiometric TiN thin films are fabricated using a dual Kaufman ion-beam source setup, without the necessity of substrate heating. These layers are remarkable compared to established forms of TiN due to high degree of crystallinity and excellent electrical conductivity. How this fabrication method can be extended to produce structured AlN, to yield robust AlN/TiN bilayer micropyramids, is described. These electrodes compare favorably to commercial TiN microelectrodes in the performance metrics important for bioelectronics interfaces: higher conductivity (by an order of magnitude), lower electrochemical impedance, and higher capacitive charge injection with lower faradaicity. These results demonstrate that the Kaufman ion-beam sputtering method can produce competitive nitride ceramics for bioelectronics applications at low deposition temperatures.
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| 3. |
- Gryszel, Maciej, et al.
(författare)
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Vertical Organic Electrochemical Transistor Platforms for Efficient Electropolymerization of Thiophene Based Oligomers
- 2024
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534.
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Tidskriftsartikel (refereegranskat)abstract
- Organic electrochemical transistors (OECTs) have emerged as promising candidates for various fields, including bioelectronics, neuromorphic computing, biosensors, and wearable electronics. OECTs operate in aqueous solutions, exhibit high amplification properties, and offer ion-to-electron signal transduction. The OECT channel consists of a conducting polymer, with PEDOT:PSS receiving the most attention to date. While PEDOT:PSS is highly conductive, and benefits from optimized protocols using secondary dopants and detergents, new p-type and n-type polymers are emerging with desirable material properties. Among these, low-oxidation potential oligomers are highly enabling for bioelectronics applications, however the polymers resulting from their polymerization lag far behind in conductivity compared with the established PEDOT:PSS. In this work we show that by careful design of the OECT geometrical characteristics, we can overcome this limitation and achieve devices that are on-par with transistors employing PEDOT:PSS. We demonstrate that the vertical architecture allows for facile electropolymerization of a family of trimers that are polymerized in very low oxidation potentials, without the need for harsh chemicals or secondary dopants. Vertical and planar OECTs are compared using various characterization methods. We show that vOECTs are superior platforms in general and propose that the vertical architecture can be expanded for the realization of OECTs for various applications.
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| 4. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes
- 2008
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Ingår i: Autophagy. - : Landes Bioscience. - 1554-8627 .- 1554-8635. ; 4:2, s. 151-175
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Forskningsöversikt (refereegranskat)abstract
- Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
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