Flexible Piezoresistive Sensors Based on PPy Particles Encapsulating Natural Flat Silkworm Cocoons

Fabricating flexible sensors with natural materials requires exquisite design and appropriate methods. In this study, a natural flat silk cocoon (FSC) was used as a flexible substrate for fabricating the piezoresistive pressure sensor. Supporting degumming was first applied to acquire sufficient internal space, and then, PPy was evenly coated on the FSC through in situ polymerization. This well-distributed coating of PPy on the surface and inside the FSC endows the assembled flexible pressure sensor with a high sensitivity (0.0633 kPa^-1 in the 0-31 kPa range, 0.0228 kPa^-1 in the 31-145 kPa range) and excellent durability (1100 cycles). This fabricated sensor is also able to respond quickly to changes in external pressure (response/recovery time of 130 ms/80 ms). Based on the excellent sensing performance and stability, this fabricated sensor can be applied to the fields of human motion monitoring, object recognition, and information transmission. The pressure sensor based on the natural FSC will receive more attention in the field of flexible wearable electronics.