Electro-Optical InGaZnO Synaptic Transistor with Solid State Electrolyte for Pain Perception

Integrating pain perception into wearable electronics or humanoid robots within artificial neuromorphic systems is highly desirable, as it allows for the identification of harmful stimuli and the generation of appropriate responses. In this study, flexible pain perception synaptic transistors is developed based on solid state ionic-liquid-cross-linking-poly (4-vinylphenol) (IL-c-PVP) electrolyte and IGZO channel with excellent electrical and photoelectric performances. Typical transistor synaptic plasticity, such as paired pulse facilitation, short-term memory, and long-term potentiation, is realized with the electrolyte comprising 40% ionic liquid, featuring a large electric-double-layer capacitance of 0.65 µF cm⁻² at 20 Hz. In addition, due to the low ion mobility and large capacity of the electrolyte, alongside the persistent photoconductivity to UV light and the high electron carrier mobility of the IGZO, the fabricated synaptic transistors demonstrated excellent pain perception capabilities, including pain threshold, peripheral sensitization, desensitization and central regulation in response to both electrical and optical stimuli with ultralow energy consumption (≈1.3 fJ per event) and desirable mechanical flexibility. Moreover, classical Pavlovian pain conditioning is successfully simulated through electro-optical co-modulation, and visual imaging in the curved state is demonstrated, highlighting the potential applications of these synaptic transistors in biomimetic nervous systems.