Benchtop Fabrication and Integration of Laser-Induced Graphene Strain Gauges and Stimulation Electrodes in Muscle on...

Muscle on a Chip devices are valuable research tools for interrogating the structure and physiology of engineered heart, skeletal, and smooth muscle tissue constructs from the molecular to the multi-cellular level. However, many existing devices rely on functional assays with limited throughput, such as optical microscopy, to measure contractility. Electrical components have been integrated to automate recordings, but their fabrication typically requires specialized equipment found in cleanroom facilities. In this work, we engineered miniature strain gauges to record the contractions of engineered skeletal muscle bundles using only benchtop fabrication equipment. We employed a commercial CO₂ laser to generate patterns of laser-induced graphene (LIG) on polyimide (PI) films. LIG was then transferred from PI to thin polydimethylsiloxane (PDMS) films to make conductive and intrinsically flexible and stretchable layers that demonstrated long-term stability under repeated cycles of stretch. We then anchored engineered skeletal muscle bundles to LIG-PDMS strain gauges and successfully measured their contraction in response to electrical stimulation, which was delivered by LIG-PI stimulation electrodes also integrated into the device. Collectively, these results demonstrate that LIG is an attractive material for rapidly and inexpensively integrating electrical components for in situ strain sensing and electrical stimulation in Muscle on a Chip devices.