Piezoelectric materials: a new dawn in neural injury repair

Neural injuries affecting the peripheral and central nervous systems remain major clinical challenges because primary tissue disruption is followed by injury-specific secondary cascades, inhibitory extracellular environments, and limited circuit reconstruction. Piezoelectric biomaterials can convert physiological micromotion or externally applied ultrasound into localized electrical cues and therefore offer a self-powered route to combine structural repair with neuromodulation. This review critically compares natural, inorganic, organic, and composite piezoelectric systems in terms of piezoelectric coefficients, representative device-level outputs, mechanical compatibility, degradation, and biosafety. We first establish the physiological basis for bioelectric regulation in peripheral nerve injury (PNI), spinal cord injury (SCI), traumatic brain injury (TBI), and ischemic stroke, emphasizing the distinct cellular and electrophysiological requirements of each lesion. We then discuss rational engineering strategies, including structural alignment, compositional modification, interface engineering, and multifunctional integration, and relate these strategies to site-specific scaffold and activation requirements. Particular attention is given to controlling the catalytic activity of multiferroic materials, standardizing electromechanical characterization, and defining translational benchmarks for manufacturing, sterilization, long-term safety, and regulatory evaluation. Overall, piezoelectric materials are promising for neural injury repair, but clinically meaningful progress will require pathology-matched design and quantitative comparison rather than optimization of piezoelectric output alone.