Self-assembly of metal-organic framework (UIO-66-NO2) and MXene for wearable and high-performance flexible pressure sensor

Wearable sensor technology has garnered increasing attention among researchers. In this study, the porous metal-organic framework containing nitroxide (UIO-66-NO2) is pasted onto MXene by hydrogen bonding and then incorporated into PVDF-HFP for electrospinning to fabricate piezoelectric membranes. The porous structure of the metal-organic frameworks significantly contributes to the alignment of electric domain orientation within the piezoelectric membranes post-polarization, and the nitro of UIO-66-NO2 helps to enhance the inductive power effect of the sensor, the piezoelectric constant of the composite piezoelectric membrane reaches 26.1 pC/N, 5.8 times that of the pure PVDF-HFP membrane (4.5 pC/N). The sensitivity reaches 20.99 V/N, which is 5.75 times that of the pure PVDF-HFP sensor (3.65 V/N). We conduct an exploration into the potential mechanisms behind the enhanced piezoelectric properties resulting from the incorporation of MXene and the metal-organic framework. The fabricated flexible pressure sensor exhibits commendable cyclic stability, boasting rapid response and recovery time (20/10.8 ms). The sensor demonstrates the capability to monitor human respiration and pulse, discern various parts of the human body and their respective amplitudes, differentiate between different materials, the pressure sensor has potential applications in human-computer interaction and health monitoring. [Display omitted] •UIO-66-NO2 is self-assembled on monolayer MXene surface via hydrogen bonding.•The “nanoconfinement effect” of UIO-66-NO2 and MXene would enhance piezoelectric effect.•The composite membrane has a piezoelectric constant (d33) of 26.1 pC/N.•The sensor has high sensitivity (20.99 V/N) and fast recovery time (10.8 ms).•The sensor is able to monitor faint breathing and pulse.