When a polymer swollen in electrolyte experiences mechanical deformation, it creates an inhomogeneous ionic distribution that causes a generation of voltage. This is theorized to be due to the difference in mobilities between cationic and anionic species, which creates a localized charge gradient when pressure is applied. We are investigating the usage of this effect to create soft gel electrical pressure sensors for soft multifunctional tactile interfaces with higher biointegratability. These may also be interesting for biointerfaces and stimulation. Some results were published in Proceedings of the SPIE (2015), Multifunctional Materials, and MRS Advances in collaboration with the University of Wollongong and the University of Cergy-Pontoise.
Piezoionic material showing conformability, transparency and strength
Diagram showing inhomogeneous ion distribution causing piezoionic effect
Piezoionic gel sensor on wrist