https://www.sciencedaily.com/releases/2022/04/220428142837.htm

These hydrogels can generate voltages when touched, but scientists did not clearly understand how -- until a team of researchers at UBC devised a unique experiment, published today in Science.

"How hydrogel sensors work is they produce voltages and currents in reaction to stimuli, such as pressure or touch -- what we are calling a piezoionic effect. But we didn't know exactly how these voltages are produced," said the study's lead author Yuta Dobashi, who started the work as part of his master's in biomedical engineering at UBC.