Flexible piezoelectric pressure sensors utilizing a low-dimensional perovskite–PVDF composite

Abstract

Technological advancements drive the demand for smart, flexible, and sustainable devices capable of integration into daily life. Pressure sensors, particularly those utilizing halide perovskites, face key challenges in sensitivity, stability, and integration with soft systems. This study focuses on the investigation of quasi-two-dimensional (2D) perovskite pressure sensors, where the perovskite is embedded within a polyvinylidene fluoride (PVDF) polymer matrix and protected by a polydimethylsiloxane (PDMS) polymer layer. The improvement in the performance of the pressure sensors is achieved through the optimization of the solvent composition, perovskite : PVDF ratio, and thickness of the PDMS layer, with a deep understanding of the morphological structure's influence on piezoelectric properties. Our perovskite layer achieves a high piezoelectric coefficient (d₃₃) of 31.26 pm V⁻¹, surpassing previously reported values for halide perovskites. Unlike previous studies, we systematically investigate the correlation between the PDMS thickness and the piezoelectric response, identifying a critical thickness threshold (∼23 μm) beyond which sensing is suppressed. The devices demonstrate pressure sensitivity in the absence of any external power source and maintain reliable performance for 1000 cycles and up to 60 days under ambient conditions. Successful integration of the sensors into soft robotic grippers while also demonstrating sensitivity to various weights highlights their potential for application in fields such as soft robotics and healthcare.