Opto-Myomatrix: μLED integrated microelectrode arrays for optogenetic activation and electrical recording in muscle tissue

Abstract

AbstractOptogenetics is a valuable and widely-used technique that allows precise perturbations of selected groups of cells with high temporal and spatial resolution by using optical systems and genetic engineering technologies. Although numerous studies have been done to investigate optogenetic tools used in the brain and central nervous system (CNS), there has been limited progress in developing similar tools for optogenetic muscle stimulation. This paper introduces Opto-Myomatrix, a novel optogenetic tool designed for precise muscle fiber control and high-resolution recording. Based on a flexible and biocompatible polymer substrate, the device incorporates an integrated µLED that delivers light at 465 nm for optogenetic stimulation and 32 low-impedance electrodes for electromyography (EMG) recording. A reflector is also added to the device to improve optical power output by nearly 100% in the direction of interest. Compared to uncoated electrical contacts, the PEDOT:PSS-coated recording electrodes possess an average impedance that is 85% lower, ensuring high signal-to-noise EMG acquisition. To evaluate the potential risk of thermal tissue damage, we measured and simulated the heat dissipation characteristics of the µLED. This analysis aimed to ensure that the maximum temperature change remains within a safe range. The Opto-Myomatrix device was implanted in transgenetic mice and successfully stimulated targeted jaw muscles, inducing movement while simultaneously capturing EMG signals.