Title:
Impedance Characterization and Modeling of Subcellular to Micro-Sized Au, Pt, TiN, and ITO Electrodes With PEDOT:PSS-Coating For Bioelectrical Interfaces
Impedance Characterization and Modeling of Subcellular to Micro-Sized Au, Pt, TiN, and ITO Electrodes With PEDOT:PSS-Coating For Bioelectrical Interfaces
Author(s)
Wang, Adam
Advisor(s)
Wang, Hua
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Abstract
The objective of the proposed research is to investigate the electrode-electrolyte interface of ultraminiaturized biocompatible electrodes. Electrode-to-cell/tissue interfaces with high biocompatibility, low-impedance, and long-term chemical and mechanical stability are of paramount importance in numerous biological and biomedical applications. For meticulous monitoring of biological parameters, there is a rapidly growing interest in sensing at sub-cellular levels with radically improved spatiotemporal resolution, which necessitates ultra-miniaturized electrodes with significant reduction in electrode contact sizes. Such aggressive electrode downsizing inevitably impacts the electrochemical interfaces, with the consequences still poorly understood. This paper reports the first systematic analysis of the interfacial electrochemical impedance spectroscopy (EIS) of electrodes comprised of a variety of biocompatible electrode materials consisting of gold (Au), platinum (Pt), indium tin oxide (ITO), and titanium nitride (TiN) coated with/without organic polymer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), with electrode diameters (D) ranging from millimeter to subcellular (<10 µm) dimensions. PEDOT:PSS coated electrodes have greater faradaic charge transfer capability and capacitive coupling compared to their uncoated counterparts. At D = 10-200 µm, PEDOT:PSS coating reduces the electrode interfacial impedance at 1 kHz by up to ×101.6 while at D > 200 µm, the effect is lessened due to dominance of solution, or bulk electroyte, and routing resistance. The low interfacial impedance of PEDOT:PSS coated electrodes make them promising candidates for next-generation bioelectrical interfaces with subcellular spatial resolution.
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Date Issued
2022-05-09
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