Ultrastable Wide-Range Capacitive Pressure Sensors with CNTs-Pinned PDMS Foam Composite Dielectrics for Intelligent Tactile Perception

Abstract

Flexible capacitive pressure sensors have attracted considerable attention for wearable electronics, intelligent robotics, and human-machine interfaces, yet achieving high sensitivity, broad pressure detection, and long-term stability remains challenging. Herein, carbon nanotubes (CNTs)-pinned porous polydimethylsiloxane (PDMS) foam composite dielectrics are developed via a facile one-step emulsion-templating strategy. The CNTs are preferentially distributed along the PDMS skeleton and pore walls, forming a CNTs-pinned architecture that is expected to reduce filler rearrangement during repeated deformation. Benefiting from the synergistic low-modulus and high-dielectric effect, the sensor achieves a pressure range of 0–450 kPa with sensitivities of 68.9 × 10–3 kPa–1, 18.9 × 10–3 kPa–1, and 8.7 × 10–3 kPa–1 in the low-, medium-, and high-pressure regions, respectively. It also exhibits a 31.3-fold enhancement in sensitivity over pristine PDMS, with a detection limit of 8.8 Pa, response/recovery times of 87/92 ms, and robust stability over 10,000 cycles. Furthermore, when integrated into a soft robotic gripper, three sensors achieve 99.4% accuracy in fruit-type classification and 99.7% accuracy in tomato storage-stage classification. This work provides a scalable strategy for engineering stable porous composite dielectrics and demonstrates the potential of tactile sensing for intelligent fruit monitoring and robotic manipulation.