Artifact-free and high-temporal-resolution in vivo opto-electrophysiology with microLED optoelectrodes

The combination of in vivo extracellular recording and genetic-engineering-assisted optical stimulation is a powerful tool for the study of neuronal circuits. Precise analysis of complex neural circuits requires high-density integration of multiple cellular-size light sources and recording electrodes. However, high-density integration inevitably introduces stimulation artifact. We present minimal-stimulation-artifact (miniSTAR) mu LED optoelectrodes that enable effective elimination of stimulation artifact. A multi-metal-layer structure with a shielding layer effectively suppresses capacitive coupling of stimulation signals. A heavily boron-doped silicon substrate silences the photovoltaic effect induced from LED illumination. With transient stimulation pulse shaping, we reduced stimulation artifact on miniSTAR mu LED optoelectrodes to below 50 mu V-pp, much smaller than a typical spike detection threshold, at optical stimulation of >50mWmm(-2) irradiance. We demonstrated high-temporal resolution (<1ms) opto-electrophysiology without any artifact-induced signal quality degradation during in vivo experiments. MiniSTAR mu LED optoelectrodes will facilitate functional mapping of local circuits and discoveries in the brain. Artifact-free opto-electrophysiology is key for precise modulation and monitoring of individual neurons at high spatio-temporal resolution. The authors present a method for eliminating stimulation artifacts in high-density micro-LED optoelectrodes for accurate functional mapping of local circuits.