Highly stretchable and robust textile-based capacitive mechanical sensor for human motion detection

Mechanically stretchable capacitive sensors are extremely promising for applications in continuous health-monitoring. Typical capacitive sensors, made from polymer and thin metal film supporters, lack interfacial adhesion or chemical bonding and have intrinsically low stretchability. Moreover, the performance of most sensors is critically affected by the conformity mismatch at the electrode and dielectric layer interface during high mechanical deformation. Many mechanical sensors have limited practical applications due to significant hysteresis, low sensitivity, and lack of reproducibility. Herein, we develop a textile-based capacitive mechanical sensor by utilizing titanium carbide-based MXene (Ti₃C₂T_x) to fabricate conductive textiles and a composite film of polystyrene (PS) fibers and ecoflex silicone as a dielectric layer. Ti₃C₂T_x showed strong bonding with the fabric owing to its rich surface chemistry, hydrophilicity, and large surface area. The MXene-coated fabric and integration of the composite film make the sensor mechanically stretchable, thus improving its sensitivity, response time, and stability. The sensor showed negligible hysteresis (∼0.2) and demonstrated a high sensitivity of 1.11 when stretched to 100 % elongation and 13.02 kPa⁻¹ when squeezed at a pressure of 200 kPa and excellent cyclic stability (1000 cycles). The sensor was further utilized for the detection of human motion when specific body movements were performed.