Multi-modulus gradient structured, self-healing, recyclable, self-adhesive capacitive flexible pressure sensor

Abstract

Flexible sensors have garnered significant attention due to their electromechanical characteristics, such as surface adaptability, extensible conformability, and tunable flexibility. Among these sensors, self-healing flexible sensors (SFS) exhibit long-term stability as they can recover their initial functionality even after suffering mechanical damage. However, these sensors face challenges in practical applications, including difficulty in balancing sensitivity and measurement range, low self-healing efficiency, and insufficient surface adaptability. To mitigate these challenges, this paper proposes a multi-modulus gradient structured, self-healing, recyclable, and self-adhesive capacitive flexible pressure sensor (MSRS-CFPS). The proposed sensor consists of liquid metal (LM) electrodes and a dielectric layer made up of three integrated self-healing polydimethylsiloxane elastomers (SPE) with different moduli, achieving a balance between high sensitivity (0.061 kPa⁻¹) and wide measurement range (65.03 kPa). The MSRS-CFPS demonstrates excellent mechanical healing efficiency (98.85 % MHE) and electrical healing efficiency (99.82 % EHE), which are achieved thanks to the excellent self-healing ability of SPEs and LM electrodes. The sensor can tightly adhere to various complex surfaces without additional fixing devices, and the SPE's elastic modulus can recover up to 91.64 % of its initial value after recycling. The MSRS-CFPS shows a high potential for applications in human motion detection and regional stress measurement.