On-Demand MXene-Coupled Pyroelectricity for Advanced Breathing Sensors and IR Data Receivers.

MXene-inspired two-dimensional (2D) materials like Ti 3 C 2 T x are widely known for their versatile properties, including surface plasmon, higher electrical conductivity, exceptional in-plane tensile strength, EMI shielding, and IR thermal properties. The MXene nanosheets coupled poly(vinylidene fluoride) (PVDF) nanofibers with d 33 ∼-26 pm V -1 are able to capture the smaller thermal fluctuation due to a superior pyroelectric coefficient of ∼130 nC m -2 K -1 with an improved (∼7 times with respect to neat PVDF nanofibers) pyroelectric current figure of merit (FOM i ). The significant enhancement of the pyroelectric response is attributed to the confinement effect of 2D MXene (Ti 3 C 2 T x ) nanosheets within PVDF nanofibers, as evidenced from polarized Fourier transform infrared (FTIR) spectroscopy and scanning probe microscopy (SPM). In subsequent studies, the practical applications of self-powered pyroelectric sensors of MXene-PVDF have been demonstrated. The fabricated flexible, hydrophobic pyroelectric sensor could be utilized as an excellent pyroelectric breathing sensor, a proximity sensor, and an IR data transmission receiver. Further, supervised machine learning algorithms are proposed to distinguish different types of breathing signals with ∼98% accuracy for healthcare monitoring purposes.