Analysis of piezoionic phenomenon in hydrogel materials and implementation for the fabrication of innovative self-powered tactile sensors

Nowadays many of the sensors used in the market take advantage of the characteristic physical behaviours of some materials to develop new devices. The piezoionic phenomenon is an effect in which applying pressure on the material generates a redistribution of ions that can be translated into a voltage and current output. This physical mechanism can be useful to describe the sensory behaviour of the skin, so its study can lead to the creation of new self-powered sensors and Smart skins as well as new robotic and prosthetic applications. This study analyses the piezoionic effect in a semi-interpenetrated polymeric network hydrogel. The impact of ionic mobility on the electrical response of the material was validated using salts with the same anion but different cation. Samples with parallel and sandwich copper electrodes were subjected to various tensile and compression tests to evaluate the electrical behaviour of the different mobile ions. In addition, the response in time to a constant force was studied to analyse the diffusivity of the ions. After the functional characterization of the material, the hydrogel was implemented as a biometric self-powered sensor for human movement. With the results obtained it has been possible to establish this type of hydrogels as an alternative to develop new tactile sensors that allow the perception of the skin as well as innovative devices useful in soft robotics, energy harvesting and biomedicine.