Flexible electronics with multifunctional stretchable pressure sensor

Flexible pressure sensors with printed interdigital electrodes are widely used due to their simple fabrication and relevance to wearable and health-monitoring applications. In this work, a multilayer piezoresistive pressure sensor is fabricated by direct ink writing on a liquid silicone substrate. Silver-paste interdigital electrodes are printed on the silicone, followed by a carbon nanotube (CNT) and thermoplastic polyurethane (TPU) (CNT/TPU) composite ink as the sensing layer. The substrate is a low-viscosity, fast-curing silicone rubber, providing a flexible yet stable base for the printed layers. The CNT/TPU ink exhibits shear-thinning rheology and excellent printability, enabling high-fidelity deposition of a uniform piezoresistive film. The sequential printing and curing process yields a well-integrated multilayer structure with good interlayer adhesion and mechanical stability. Sensor testing shows a high sensitivity of ~0.054 kPa-1 and a wide detection range of 0–100 kPa (with a linear response up to ~80 kPa). The dynamic performance is fast: the response time is about 65 ms and the recovery time about 96 ms. Hysteresis under cyclic loading is modest (~10.3%), indicating reliable repeatability. The device is thermally robust: baseline resistance changes by less than 10% over 25–60 °C, despite the typical temperature dependence of polymer composites. This stable electromechanical behavior compares favorably with other CNT‐based sensors. Our all-printed multilayer device offers a balanced performance with simpler fabrication. These combined attributes make the sensor well-suited for flexible electronics. In particular, such printed CNT/TPU pressure sensors are promising for wearable electronics, soft robotics, and health monitoring applications.