Highly Deformable Microfluidic Sweat Sensors Fabricated via Roll‐to‐Roll Scalable Processes

Disposable sweat sensors are essential tools for sweat‐based diagnostics, enabling comprehensive insights into sweat physiology. To support widespread applications and large‐scale studies, it is critical to develop sensors that are mass‐producible, user‐friendly, and capable of delivering consistent performance. Roll‐to‐roll processing enables scalable, and uniform manufacturing of flexible microfluidic sensors, addressing the throughput and complexity limitations of traditional methods such as photolithography and vacuum deposition. In this study, we present a highly deformable microfluidic sweat sensor fabricated via roll‐to‐roll processes. The sensor is constructed by laminating sweat‐sensing electrodes patterned on thermoplastic polyurethane with polydimethylsiloxane microstructures to form microfluidic channels. By adapting screen printing and hot imprinting techniques for roll‐to‐roll manufacturing, high‐throughput production is achieved. This method yields hundreds of customizable sensors per roll, exhibiting excellent mechanical flexibility, reproducible sensing performance, and scalability. Furthermore, the developed sweat sensor is demonstrated during wear on the fingertip, showcasing its capability for real‐time sweat rate monitoring on an anatomically curved surface. These advancements position the roll‐to‐roll‐fabricated sweat sensor as a promising solution for large‐scale, real‐time sweat diagnostic applications.