Electrodeposition of PEDOT:ClO4 on non-noble tungsten microwire for nerve and brain recordings

Tungsten microwires are commonly used in neuroscience for their high mechanical strength, flexibility, which allows tailoring them to brain and peripheral nerve implantations, and cost-effectiveness compared to other electrode materials. However, challenges such as high impedance and foreign body reactions limit their use as acute and chronic electrophysiology tools. In this work, we propose a novel method for successfully coating tungsten microwires with PEDOT (poly(3,4-ethylenedioxythiophene)) doped with perchlorate anions ClO4− using electropolymerization. Pre-treatment of the microwires with annealing resulted in the formation of a WO3 coating that facilitated the nucleation and deposition of PEDOT, which was more homogeneous than that on gold microwires under the same conditions. In vitro, PEDOT decreased the impedance and increased the capacitance compared to bare tungsten microwires. In vivo, the PEDOT coating enhanced the signal-to-noise ratio and reduced the standard deviation of noise in acute preliminary electrophysiology recordings of spontaneous activity in the brain and evoked activity in the sciatic nerve of the rat.