Piezoionic effect makes sense for ionic skins

Scientists have worked out how the piezoionic effect works in hydrogels, an advance that could further the application of ionic skins to prosthetic arms or robot hands.

Ionic skins are designed to mimic the sensing capabilities of natural skin and are made of flexible, biocompatible hydrogels that use ions to carry an electrical charge. In contrast to smart skins made of plastics and metals, the hydrogels have the softness of natural skin and are more comfortable to wear.

These hydrogels can generate voltages when touched - the piezoionic effect - but scientists did not clearly understand how until a team at the University of British Columbia (UBC) devised a unique experiment that is published in Science.

Working under the supervision of UBC researcher Dr. John Madden, the study’s lead author Yuta Dobashi devised hydrogel sensors containing salts with positive and negative ions of different sizes. He and collaborators in UBC’s physics and chemistry departments applied magnetic fields to track precisely how the ions moved when pressure was applied to the sensor.