Anschutz, P. | bioRxiv Science

bioRxiv2024

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

ObjectiveOptogenetics 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. This study aims to develop Opto-Myomatrix, a novel optogenetic tool for precise muscle fiber control and high-resolution electrophysiological recording. MethodBased on a flexible and biocompatible polymer substrate, the device incorporates an integrated {micro}LED that delivers light at 465 nm for optogenetic stimulation and 32 PEDOT:PSS-coated electrodes for electromyography (EMG) recording. We also added a reflector to improve optical power output. ResultsThe fabricated Opto-Myomatrix device achieves an optical output intensity as high as 129.46 mW/mm2 in the direction of interest, which is enhanced by nearly 100%. The PEDOT:PSS-coated electrodes exhibit 85% lower impedance than uncoated contacts, enabling high signal-to-noise EMG acquisition. We investigated heat dissipation characteristics of the {micro}LED through measurements and finite element simulations, confirming that temperature changes remain within safe limits. The Opto-Myomatrix device was implanted in transgenetic mice and successfully stimulated targeted jaw muscles, inducing movement while simultaneously capturing EMG signals. ConclusionThe Opto-Myomatrix effectively combines precise optical stimulation and high-quality EMG recording in a flexible and biocompatible device, focusing on optogenetic applications in muscle. SignificanceWhile optogenetic tools are well-established for brain and central nervous system (CNS) research, the development of Opto-Myomatrix addresses a critical gap by enabling precise muscle fiber control and high-resolution recording for advancing neuromuscular studies.

bioengineering↗

bioRxiv2023

Myomatrix arrays for high-definition muscle recording

Neurons coordinate their activity to produce an astonishing variety of motor behaviors. Our present understanding of motor control has grown rapidly thanks to new methods for recording and analyzing populations of many individual neurons over time. In contrast, current methods for recording the nervous systems actual motor output - the activation of muscle fibers by motor neurons - typically cannot detect the individual electrical events produced by muscle fibers during natural behaviors and scale poorly across species and muscle groups. Here we present a novel class of electrode devices ("Myomatrix arrays") that record muscle activity at unprecedented resolution across muscles and behaviors. High-density, flexible electrode arrays allow for stable recordings from the muscle fibers activated by a single motor neuron, called a "motor unit", during natural behaviors in many species, including mice, rats, primates, songbirds, frogs, and insects. This technology therefore allows the nervous systems motor output to be monitored in unprecedented detail during complex behaviors across species and muscle morphologies. We anticipate that this technology will allow rapid advances in understanding the neural control of behavior and in identifying pathologies of the motor system.

neuroscience↗