A robust platform for textile integrated gas sensors

Fabrication, textile integration and post-weaving characterization of a robust platform for monolithically integrated, low-power gas and temperature sensing are presented. The platform, consisting of an interdigitated planar capacitor for gas sensing and a resistive temperature sensor, is fabricated on a 50 μm thick flexible Kapton E® film using a simple roll-to-roll compatible process, and particularly targets disposable textile products, such as smart air filters, and medical garments. In order to demonstrate the versatility of the platform, the sensors are functionalized for humidity sensing by spray-coating of a 10 μm thick Cellulose Acetate Butyrate (CAB) polymer layer. In commercial machine weaving processes, any functional device undergo significant mechanical deformation, mostly due to high bending, and shear forces associated with the process. Bending radii in textiles can be as small as 165 μm during weaving, corresponding to a strain of about 15%. This imposes stringent mechanical requirements on the textile integrated sensors. Furthermore, the sensors integrated in textiles are exposed to harsh physical and chemical environments during operation. To avoid device failure, the sensor active area is fully encapsulated for protection during singulation, weaving, and operation, and is demonstrated to retain full functionality after weaving and repeated strain and stress tests. Despite the simple sensor structure, rapid and accurate sensor response is demonstrated in differential sensing mode.