A negative-response strain sensor towards wearable microclimate changes for body area sensing networks

Wearable and stretchable strain sensors have attracted much attention for their unique applications in moni-toring human motion and health. However, state-of-the-art sensors lack sensing reliability on temperature and humidity changes at the wearable microinterface, leading to suboptimal sensing accuracy in body area sensing networks. For that, we design and fabricate a strain sensor using silk/polyurethane composite yarns with a core-sheath structure. The silk is modified using graphene with the assistance of 3-glycidyloxypropyl trimethoxy silane as coupling agent. The sensor exhibits fast response speed (i.e., 80 ms), high durability (>1500 cycles), remarkable linear sensing feature (R2 = 99.8 %) throughout the whole working range, and negative resistance response towards strain deformation. More importantly, the sensor performance will not be affected by tem-perature and humidity changes in typical use conditions. Testing is conducted and sensor responses in various body motions are also reported. In addition, a demonstration for the real-time body area sensing network using the fabricated sensor is provided. Experimental results from this study show that the fabricated strain sensor will have huge potentials for future personalized healthcare and public health management.