Mechanoreceptor‐Inspired Dynamic Mechanical Stimuli Perception based on Switchable Ionic Polarization

• Published in: Advanced functional materials 2021-06, Vol.31 (23), p.n/a
• Main Authors: Yoon, Hong‐Joon, Lee, Dong‐Min, Kim, Young‐Jun, Jeon, Sera, Jung, Jae‐Hwan, Kwak, Sung Soo, Kim, Jihye, Kim, SeongMin, Kim, Yunseok, Kim, Sang‐Woo
• Format: Article
• Language: English
• Subjects: Communications systems; communicators; Debye length; Deformation effects; dynamic perception; Electrification; Gelatin; Haptic interfaces; Hydrogels; ion dynamics; ionic hydrogels; Ionic mobility; Materials science; mechanical stimuli; Performance enhancement; piezoionic effect; Polarization; Sensors; Stimuli; triboelectric effect
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202100649

Diverse touch experiences offer a path toward greater human–machine interaction, which is essential for the development of haptic technology. Recent advances in triboelectricity‐based touch sensors provide great advantages in terms of cost, simplicity of design, and use of a broader range of materials. Since performance solely relies on the level of contact electrification between materials, triboelectricity‐based touch sensors cannot effectively be used to measure the extent of deformation of materials under a given mechanical force. Here, an ion‐doped gelatin hydrogel (IGH)‐based touch sensor is reported to identify not only contact with an object but also deformation under 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. The rationally designed ion‐doped gelatin hydrogels (IGHs) provide dynamic tactile perception under consecutive events of mechanical stimuli, benefiting from the combined characteristics of triboelectric and piezoionic effects. Through broader theoretical studies on ion dynamics, remarkable sensitivity in deformative circumstances is achieved. The developed dynamic tactile sensing‐based communicator enables simultaneous recognition of pressure and texture through in‐depth analyses of ion dynamics.