Evaluation of Polydimethylsiloxane-Nb₂C MXene Conductive Polymer Composite Based Piezoresistance Sensors Parameters and Applications

Abstract

Flexible pressure or strain sensors are widely researched for soft robotics, dataglove, biomedical, and human–machine interaction (HMI) applications. Among three types of piezosensors, piezoresistance pressure sensor is easy to fabricate and require simple readout circuit. Flexible piezoresistance sensors (fPRSs) were fabricated predominantly from conductive polymer composites (CPCs) by dispersing conductive fillers in flexible insulating polymer matrices. Piezoresistors with 1-D and 2-D conductive fillers at percolation threshold concentration were shown promising results in both strain and pressure sensing. Here, different weight % of 2-D Nb2C MXene conductive fillers dispersed in polydimethylsiloxane (PDMS) matrix were fabricated by blending method, and these composites were screen printed as piezoresistors and measured their resistance in shunt mode. Present piezoresistor preparation method is very simple, easy to scale up, and cost effective. Nb2C MXenes were made by Al etching from Nd2AlC, and Nb2C were characterized by various analytical tools to study morphology, crystal structure, and interlayer separation. Among the two fPRSs studied, PDMS-80 wt% Nb2C composite sensor shows relatively low elastic modulus (0.215 MPa) or high flexibility, and high tensile strength (0.434 MPa). The fRPS also show high gauge pressure sensitivity of 0.61 kPa<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula> in a linear working range of 0–4 kPa, and fast response/recovery time (0.42/0.84 s). The sensor exhibits good response in radial artery pulse profile measurement (for biomedical applications), flex-release cycles of wrist and fingers motion (for hand gesture measurement applications in robotic and virtual reality applications), and touch sensing capability (for HMI applications).