Multiscale piezoionic transduction: From materials engineering to bioelectronic sensing and therapeutic applications

Mechanical deformation in living tissues generates electrical cues through ion transport, yet conventional bioelectronic interfaces remain poorly matched to soft, hydrated environments. Piezoionic materials offer a compliant alternative by converting deformation into electrical signals through mechanically perturbed electrochemical potentials and coupled ion-solvent transport rather than lattice polarization. This review examines the physicochemical basis of piezoionic transduction and multiscale strategies spanning ion-polymer interactions, nanoconfined channels, structural gradients, and electrode interfaces. These designs regulate ion selectivity, transport kinetics, electrical output, and energy conversion, enabling physiological sensing, multimodal perception, energy harvesting, and therapeutic intervention. Reported outputs span millivolts to hundreds of millivolts and nanoamperes to milliamperes, and have activated peripheral and autonomic nerves, driven electrochemical drug release, and supported cartilage, bone, and wound repair in vivo. Unstable output and the unquantified dose reaching tissue remain the principal obstacles to clinical devices that integrate diagnosis and therapy.