Simultaneous Optimization of Sensitivity and Linearity for Flexible Pressure Sensor via Coupling Effect between Microstructures and Flat Substrate Component

Abstract

Flexible piezoresistive pressure sensors with the advantages of a simple structure and facile signal acquisition have attracted considerable interest in various application fields. Although the piezoresistive layers have been widely explored to develop high-performance sensors, the trade-off between sensitivity and linearity has yet to be fully resolved. In this work, a CNT/ PDMS-based piezoresistive layer with the coupling effect of the microdomes and the flat substrate component is proposed to simultaneously optimize the sensitivity and linearity range of piezoresistive sensors. Different from conventional dome-based piezoresistive layers, the microdomes and substrate of the proposed layer can be codeformed to compensate for the resistance variation attenuation resulting from the stiffening effect of compressed soft materials. Upon the appropriate conductivity and elastic modulus of the piezoresistive layer, the sensitivity and linearity range of the sensor can be improved simultaneously. Moreover, the coupling effect of the microdomes and the substrate can be regulated by constructing gradient conductivity and elastic modulus, which enables further optimization of the sensing performance with a high sensitivity of 70.42 kPa −1 in an ultrawide linearity range of 0−950 kPa (R 2 = 0.99). The excellent sensing performance enables the sensor as a diverse wearable platform, which can not only precisely monitor various physiological signals (e.g., finger bending, walking, running, etc.) but also transmit Morse code information by simply switching the finger bending behaviors. We believe that the proposed sensor along with the optimization strategy can be of great potential for developing high-performance piezoresistive sensors for versatile wearable applications in the future.