Mechanoreceptor-Inspired Gelatin Hydrogel Sensor Based on Switchable Ionic Polarization

Triboelectricity-based touch sensors are great advantages in terms of cost, simplicity of design, and use of a wide range of materials. However, it is hard to measure the extent of deformation of materials since the performance solely relies on the level of contact electrification between materials. To overcome this limitation, we introduce an ion-doped gelatin hydrogel (IGH)-based touch sensor that can measure not only contact with objects but also deformation by a certain level of force. Switchable ionic polarization of the gelatin hydrogel is found to be instrumental in allowing for different sensing mechanisms when it is contacted and deformed. The results show that ionic polarization relies on conductivity of the hydrogels. Quantitative studies using voltage sweeps demonstrate that higher ion mobility and shorter Debye length serve to improve the performance of the mechanical stimuli-perceptible sensor. It is successfully demonstrated that this sensor offers dynamic deformation-responsive signals that can be used to control the motion of a miniature car. This study broadens the potential applications for ionic hydrogel-based sensors in a human–machine communication system.<br/>To take advantage of these properties of IGH, we developed dynamic mechanical stimuli-perceptible sensor capable of accommodating continuous tactile information about contact and deformation events. Dynamic tactile sensing-based communication was successfully demonstrated. This study broadens the potential applications for ionic hydrogel-based sensors in a human–machine communication system.