Self-healing pseudo–piezoelectric pressure sensors from sustainable and recyclable materials

Abstract

Advances in pressure sensing technologies are driven by the growing demand for flexible, lightweight, and highly sensitive devices for wearable electronics, robotics, and human–machine interfacing. While conventional piezoresistive, capacitive, and piezoelectric sensors have been successfully used in applications, they often struggle with mechanical rigidity, signal instability, and limited compatibility with soft systems. In this study, we present a pseudo–piezoelectric pressure sensor that combines both self-healing and sustainable materials while being designed for touch-level detection. Conductive and flexible films were prepared by blending sustainable and recyclable materials in water: a biopolymer (chitosan) and a natural deep eutectic solvent (NADES) as a plasticizer. The advantage of the elastomer is its mechanical degradation (scars, cracks, and tears) can be self-healed. A proof-of-concept sensor was fabricated using a simple bilayer architecture by integrating a conducting polymer (pPDS) into one of the elastomer layers to enable asymmetric charge dynamics. The sensitivity of the resulting device was 128.4 mV kPa⁻¹. The sensitivity was also reliable and the sensor's physical damage caused by over stretching could be self-healed. These results underscore the promise of iontronic sensors that exploit interfacial ionic mobility and electrostatic coupling, offering a sustainable pathway toward next-generation tactile sensors for soft, low-force applications.