A Stretchable Microneedle Electrode Array for Stimulating and Measuring Intramuscular Electromyographic Activity

We have developed a stretchable microneedle electrode array (sMEA) to stimulate and measure the electrical activity of muscle across multiple sites. The technology provides the signal fidelity and spatial resolution of intramuscular electrodes across a large area of tissue. Our sMEA is composed of a polydimethylsiloxane (PDMS) substrate, conductive-PDMS traces, and stainless-steel penetrating electrodes. The traces and microneedles maintain a resistance of less than 10 kQ when stretched up to a ~63% tensile strain, which allows for the full range of physiological motion of feline muscle. The device and its constituent materials are cytocompatible for at least 28 days in vivo. When implanted in vivo, the device measures electromyographic (EMG)activitywith clear compound motor unit action potentials. The sMEA also maintains a stable connection with moving muscle while electrically stimulating the tissue. This technology has direct application to wearable sensors, neuroprostheses, and electrophysiological studies of animals and humans.