Thermo-Adaptive Tunable Color Display with an Artificial Synapse Based on Ion-Gel Transistor

While there has been considerable progress in developing artificial synapses to mimic the human nervous system for bio-signal transmission, synapses with thermo-adaptive coloration and temperature-driven soft actuators are rarely reported. In this work, we introduce a photonic neuro-actuating synaptic skin that enables temperature-responsive synaptic signal transmission, color change, and actuation. We first developed a thermoresponsive display synapse using a 3-terminal ion-gel transistor, which incorporates an ion channel composed of two-dimensional (2D) titanium carbide (Ti₃C₂T_X) MXene mixed with poly(3,4-ethylenedioxythiophene) (styrenesulfonate) (PEDOT:PSS) and a thermo-adaptive block copolymer (BCP) photonic crystal (PC) gate insulator. The transistor exhibits temperature-dependent synaptic behavior accompanied by corresponding structural color changes, resulting in a thermo-adaptive display synapse. A 3 × 3 array of these synapses integrated with Joule heaters demonstrates control of each pixel through thermoresponsive structural colors and synaptic outputs. The synaptic output current generated from the MXene/PEDOT:PSS based ion-gel transistor can be converted and amplified into a voltage signal, which powers a soft actuator linked to our device, thereby enabling temperature-dependent actuation linked to the synaptic performance. This study presents a thermo-adaptive photonic neuro-actuating artificial skin, mimicking muscle-combined neuronal human skin with visualization capabilities.