Impedance Characterization and Modeling of Subcellular to Micro-sized Electrodes with Varying Materials and PEDOT:PSS Coating for Bioelectrical Interfaces

Electrode-to-cell/tissue interfaces with high biocompatibility, low impedance, and long-term chemical mechanical stability are of paramount importance in numerous biological biomedical applications. For meticulous monitoring parameters, there is a rapidly growing interest sensing at subcellular levels radically improved spatiotemporal resolution, which necessitates ultra-miniaturized electrodes significant reduction electrode contact sizes. Such aggressive downsizing inevitably impacts the electrochemical interfaces, consequences still poorly understood. This paper reports first systematic analysis interfacial impedance spectroscopy comprising variety biocompatible materials consisting gold (Au), platinum (Pt), indium tin oxide, titanium nitride (TiN) coated with/without an organic polymer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), diameters (D) ranging from millimeter to (<10 ?m) dimensions. PEDOT:PSS-coated have greater Faradaic charge-transfer capability capacitive coupling compared their uncoated counterparts. At D = 10–200 ?m, PEDOT:PSS coating reduces 1 kHz by up ×101.6, while > 200 effect lessened due dominance solution, or bulk electrolyte, routing resistance. The makes them promising candidates for next-generation bioelectrical spatial resolution.