Advanced Flexible Physical Sensors with Independent Detection Mechanisms of Pressure and Strain Stimuli for Overcoming Signal Interference

Abstract

Flexible and wearable physical sensors have gained significant interest owing to their potential in attachable devices, electronic skin, and multipurpose sensors. The physical stimuli of these sensors typically consist of vertically and horizontally applied pressures and strains, respectively. However, owing to their similar response characteristics, interference occurs between the two types of signals detected, complicating the distinction between pressure and strain stimuli, leading to inaccurate data interpretation and reduced sensor specificity. Therefore, we developed a dual-sensing-mode physical sensor with separate response mechanisms for the two types of physical stimuli based on a unique structural design that can independently induce changes in the piezocapacitance and piezoresistance for pressure and strain stimuli, respectively. The asterisk-shaped piezoresistive pathway (electrode), designed for multifunctionality, effectively detected the intensity and direction of tensile deformation, and an elastomeric sponge structure positioned between the two electrodes detected the pressure signals via changes in capacitance. This dual-sensing-mode sensor offers clearer signal differentiation and enhanced multifunctionality compared to those of traditional single-mode sensors. Additionally, extensive experimentation demonstrated that our sensor has a good sensitivity, high linearity, and stability in detecting signals, proving its applicability for sophisticated monitoring and control tasks that require the differential detection between pressure and deformation signals.