A low-cost, easy-fabricating stretchable microneedle-electrode array for intramuscular recording and stimulation

The application of intramuscular electrode technology to a large muscle area, with the inter-electrode distance maintained, has the potential to increase both the controllability and observability of the muscle. To address such a need, this paper presents a simple method for fabricating a novel type of stretchable microneedle-electrode array (sMNEA). The sMNEA is formed by embedding micro-sized, gold-coated nail-head pins between two polydimethylsiloxane (PDMS) layers. The nail-head pins function as microneedle electrodes which are sharp enough to penetrate a muscle easily, while the PDMS substrate holds each electrode at a fixed position, conforms to the muscle surface curvature, and stretches along with muscle deformation. Fabrication of the device is cost effective and has a turnaround time of a few hours. The resulting device is robust to bending and stretching, and its placement on and electrode insertion into a muscle are easy and efficient.