Piezoionic mechanoreceptors: Force-induced current generation in hydrogels

TLDR

The human somatosensory network relies on ionic currents to sense, transmit, and process tactile information, and piezoionic currents can vary from milliseconds to hundreds of seconds, mirroring rapid‑ and slow‑adaptation mechanisms. The study investigates hydrogels that transduce pressure into ionic currents to create a piezoionic skin. Patterned hydrogel films with gradients of fixed charge transduce pressure into ionic currents, generating voltage offsets similar to cell potentials. The piezoionic currents elicit direct neuromodulation and muscle excitation, with magnitude and duration governed by cationic and anionic mobility, enabling self‑powered, ultrasoft mechanoreceptors that produce charge densities four to six orders of magnitude higher than triboelectric and piezoelectric devices.

Abstract

The human somatosensory network relies on ionic currents to sense, transmit, and process tactile information. We investigate hydrogels that similarly transduce pressure into ionic currents, forming a piezoionic skin. As in rapid- and slow-adapting mechanoreceptors, piezoionic currents can vary widely in duration, from milliseconds to hundreds of seconds. These currents are shown to elicit direct neuromodulation and muscle excitation, suggesting a path toward bionic sensory interfaces. The signal magnitude and duration depend on cationic and anionic mobility differences. Patterned hydrogel films with gradients of fixed charge provide voltage offsets akin to cell potentials. The combined effects enable the creation of self-powered and ultrasoft piezoionic mechanoreceptors that generate a charge density four to six orders of magnitude higher than those of triboelectric and piezoelectric devices.