A Self-Detection Mechanism Toward Stable Multiple Perception of Ionic Skins

Ionic skins (I-skins) hold significant potential for mimicking the complex sensory functions of human skin. However, they suffer from unstable sensing performance because the water content and temperature of I-skins are susceptible to the surrounding environment. Here, a self-detection sensing mechanism designed to address this critical issue, ensuring stable perception of multiple stimuli in I-skins, is introduced. It is demonstrated that gradient polyelectrolyte (GP) conductors possess two parameters—resistance and self-induced potential—that are responsive to temperature and water content. Through establishing the functional relations of resistance and potential against temperature and water content based on the Nernst−Planck and Arrhenius equations, respectively, the temperature and water content of resulting GP I-skins can be self-detected/calculated in real-time from the measured resistance and potential signals. Such self-detection capability allows GP I-skins not only to self-calibrate their sensing parameters for accurate detection of mechanical stimuli across varying environmental conditions but also to discern surrounding temperature and humidity in accordance with Flory−Rehner theory. This self-detection sensing mechanism offers a powerful tool for developing I-skins capable of stable perception of multiple stimuli in changing environments without complex and undesired encapsulation.