Natural bamboo leaves as dielectric layers for flexible capacitive pressure sensors with adjustable sensitivity and a broad detection range

Abstract

Developing a high-performance capacitive sensor for diverse application scenarios has posed requirements for the sensor to have high sensitivity, broad detection range, and cost-effectiveness. In this experiment, a flexible pressure sensor with a high sensitivity of 2.08 kPa⁻¹ at pressure lower than 1 kPa, as well as a wide working range of 0–600 kPa and remarkable stability (for at least 4000 cycles), was designed. In the device structure, silver nanowires (Ag NWs)/MXene-composite-coated polydimethylsiloxane (PDMS) and natural bamboo leaves at different growth stages were used as the electrode and the micro-structured dielectric layers, respectively. The rough surface of the composite conductive materials and the hierarchical microstructure of the bamboo leaves ensured a high sensitivity and broad pressure range of the sandwich-structured sensor, and the different sizes of the microstructures yielded adjustable sensitivity of the sensor. Furthermore, the outstanding performance of the proposed device made it possible to detect the actual object load, human physical stimuli, and proximity distance, demonstrating applications of flexible and wearable devices in various fields, such as weight/force tapping, breath/wrist pulse/speech, joint bending, and approach distance.