A flexible capacitive pressure sensor with high performance based on synergy of both surface and porous microstructures
摘要
High-performance flexible pressure sensors have garnered significant scientific interest owing to their potential applications in wearable devices. However, realizing flexible sensors with both high sensitivity and wide sensing range is still challenging due to material and structural limitations. In this paper, a flexible capacitive pressure sensor with high sensitivity and a wide sensing range along with a facile preparation process is presented. The proposed sensor consists of a porous polydimethylsiloxane (PDMS) dielectric layer with surface microstructures and two microstructured PDMS electrodes. Microstructures on the surfaces of both the electrode and dielectric layer were prepared by a two-step indocalamus leaf replicated molding process. By evaporating the deionized water previously mixed into the PDMS solution, the interior microvoids in the PDMS dielectric layer were successfully created during the curing process of the PDMS. Microstructures on the surfaces of the electrodes and dielectric layer reduce contact stiffness via increased interfacial compliance, and the internal porosity in the dielectric layer enhances bulk compressibility, which synergistically improves the electromechanical performance of the presented sensor. Specifically, the sensor exhibits a high sensitivity of 3.307 kPa−1, a wide sensing range of 100 kPa, a fast response time of less than 40 ms, and high durability and stability over 10,000 load cycles. In addition, several practical applications of the prepared sensor in human activities detection and continuous cardiopulmonary waveform acquisition are presented. The high sensitivity and wide sensing range of the designed sensor confirm a broad application prospect in healthcare instruments and wearable electronics.