Stretchable and Sensitive Strain Sensors Based on CB/MWCNTs–TPU for Human Motion Capture and Health Monitoring

Flexible strain sensors have attracted significant attention in the wearable electronic device field, owing to their exceptional ductility, sensitivity, and durability compared to rigid strain sensors. However, the limited strain detection range or sensitivity has hindered their widespread application. In this study, a flexible strain sensor is fabricated by screen-printing a conductive carbon black ink layer on a conductive flexible composite layer made of thermoplastic polyurethane and multiwalled carbon nanotubes. Both kirigami-patterned and fingerprint-patterned structures are introduced to the architecture of sensors; while the former is designed for the improvement of strain sensing range, the latter serves for the enhancement of sensitivity and interfacial adhesion. It is demonstrated that the sensor achieves high sensitivity with a gauge factor of up to 5705.53 and has a wide strain sensing range from 0 to 150%. Besides, the sensor also shows good durability (6000 stretching–releasing cycles) and a fast response time of ∼220 ms. The excellent sensor performance of the flexible strain sensor suggests promising applications in human–computer interaction, medical health monitoring, and motion capture.