The fabrication of low-impedance nanoporous gold multiple-electrode arrays for neuralelectrophysiology studies

Abstract

Neural electrodes are essential tools for the study of the nervous system and relateddiseases. Low electrode impedance is a figure of merit for sensitive detection ofneural electrical activity and numerous studies have aimed to reduce impedance.Unfortunately, most of these efforts have been tethered by a combination of poorfunctional coating adhesion, complicated fabrication techniques, and poor fabricationrepeatability. We address these issues with a facile method for reliably producingmultiple-electrode arrays with low impedance by patterning highly adherent nanoporousgold films using conventional microfabrication techniques. The high surfacearea-to-volume ratio of self-assembled nanoporous gold results in a more than25-fold improvement in the electrode–electrolyte impedance, where at 1 kHz, 850 kΩ impedance for conventional Au electrodes is reduced to 30 kΩ for nanoporous gold electrodes. Low impedance provides a superior signal-to-noise ratio fordetection of neural activity in noisy environments. We systematically studied theeffect of film morphology on electrode impedance and successfully recorded fieldpotentials from rat hippocampal slices. Here, we present our fabrication approach, therelationship between film morphology and impedance, and field potential recordings.