Flexible Strain Sensor Enabled by Carbon Nanotubes-Decorated Electrospun TPU Membrane for Human Motion Monitoring

High-performance flexible strain sensors are gaining more and more attention with their bespoken detection range, excellent sensing performance, and good stability, which are highly desired in wearable electronics. Herein, a thermoplastic polyurethane elastomer (TPU) fibrous membrane is prepared as a flexible substrate by electrostatic spinning technology, then a coating of polydopamine is formed through fast synthesizing the dopamine on TPU fibrous membrane surface and loaded with carbon nanotubes (CNTs) to develop an extremely sensitive flexible strain sensor. The flexible sensor prepared by TPU fibrous membrane coated with polydopamine layer has an outstanding sensibility under the pulling force (Gauge Factor of 10 528.53 with 200% strain), rapid reaction time (188-221 ms), wide sensing range (up to 200%), good stability, and durability. The theoretical studies reveal the underlying cause for the high sensitivity and the inherent relationship between the amount of conducting routes and the length between adjacent conducting fillers in the sensor. The demonstration of the device shows a promising application to sense human motion at various locations of the body, with the accurate and stable electrical signal output generated at corresponding motion.