Electrochemical Impedance Spectroscopy at Well‐Controlled dc Bias for Nanoporous Platinum Microelectrodes in Rat Embryo Brain

Abstract

AbstractNanoporous Pt with extremely small (1–2 nm) and uniform nanopores, L2‐ePt, is electrochemically investigated in rat embryo brain. In a comparative study under precise control of electrochemical potential, an electrochemical cell beneath the brain surface is constructed by introducing flat and nanoporous Pt twisted wires around which Ag/AgCl is wound. L2‐ePt and flat Pt in the brain are compared with each other by conventional voltammetry and electrochemical impedance spectroscopy at the dc bias, which is carefully selected to minimize faradaic interference. The electrochemical behavior at L2‐ePt implanted into embryo brain is immune to severe passivation and is closer to an ideal capacitor than flat Pt. A lower electrode impedance of L2‐ePt leads to less potential drop at the interface between the electrode and the extracellular solution, protecting the implanted system from unwanted faradaic reactions. Various aspects, including the low electrode impedance and electrochemical stability in embryo brain, suggest that L2‐ePt is a promising electrode material for effectively stimulating distant neuronal cells and recording local field potential signals.