Investigation of the photoelectrochemical effect in optoelectrodes and potential uses for implantable electrode characterization.

The combination of optical stimulation and electrical recording is commonly employed in neuroscience research. Researchers using optogenetics are familiar with the photo-induced "artifacts" that arise from illumination of an electrode array. We sought to characterize this photoelectrochemical (PEC) effect to understand the underlying mechanism seen on NeuroNexus optoelectrodes. In doing so, we discovered that the phenomenon is inversely proportional to electrode site area in the same manner as electrical impedance measurements. We have applied the PEC effect as a method of electrode evaluation and show that a PEC measurement system can be both faster and more effective than impedance at sensing defects in high-throughput biomedical device testing.