ADVANCEMENTS IN PIEZOELECTRIC NANOMATERIALS FOR WEARABLE SENSOR APPLICATIONS

Abstract

The fast development of wearable electronics for human health monitoring, human-machine interaction, and Internet of Things (IoTs) have revealed a crucial bottleneck: the reliance on rigid, finite-lifetime batteries that limit miniaturisation, autonomy, and long-term wearability. Piezoelectric nanomaterials have emerged as uniquely promising candidates to overcome this barrier by directly transducing ambient mechanical stimuli, such as body motion, pulse vibration, respiration and muscle contraction into usable electrical signals that power and sense simultaneously. Recent progress in the last decade of one-dimensional nanowires, two-dimensional nanosheets, electrospun nanofibers and hierarchically engineered nanocomposites has brought piezoelectric devices from rigid ceramic discs to soft skin-conformal platforms for continuous body-integrated sensing. This systematic review incorporates sixty-six primary studies across four material families, zinc oxide nanostructures, PVDF and P polymer systems, barium titanate and lead-free perovskite composites, and two-dimensional nanomaterial hybrids, to evaluate their performance, durability, and translational potential for wearable sensor applications. The synthesis shows a clear performance trend in the period considered. The PDMS-encapsulated double sided ZnO nanowire arrays produce 30 V and 300 nA, with a maximum power density of 0.390 mW cm-2. The hierarchical ZnO nanorod textiles have a sensitivity of 0.62 V kPa-1 and a detection limit of 8.71 Pa . Electrospun P nanofibers have better sensitivity (5.76 V kPa−1) and a piezoelectric coefficient (−21.6 pC N−1) than previous polymer systems, whereas PVDF–NaNbO3 all-fiber nanogenerators show an extreme fatigue life surviving at 3.4 V and 4.4 μA after 1 million compression cycles at 0.2 MPa. Lead-free BaTi0.88Sn0.12O3 composites reach 1.23 V N−1 with 41.0 nA N−1, while KH550 functionalised BaTiO3 in polyacrylonitrile nanofibers provides up to 12.33 V and 1.63 V N−1, overcoming toxicity concerns without excessive performance penalties. MXene hybrids exhibit ultralow detection limits of 1-1.5 Pa with millisecond-level response, and triboelectric-piezoelectric multilayer films deliver 22.9 V and 15.1 $\mu$W peak output for sports rehabilitation. The most important development is in clinical translation. A wearable piezoelectric blood-pressure sensor was validated in 35 subjects, aged 20–80 years, with 175 paired measurements against a commercial sphygmomanometer. The mean differences were −0.89 ± 6.19 mmHg for systolic and −0.32 ± 5.28 mmHg for diastolic pressure, close to the accuracy thresholds of cuff-based reference methods. This review synthesises materials innovation, system-level engineering and clinical-grade validation to identify three emerging design principles, multiscale material engineering, system-level textile integration, and clinical validation as the discriminating benchmark, that will be decisive in turning piezoelectric nanomaterial wearables from research milestones into foundational components of next-generation personalised healthcare infrastructure.