Room-Temperature-Integrated Flexible Diffusive Oxide Memristors for Artificial Nociceptive Systems

Novel areas of human–computer interaction and intelligent robotics are rapidly boosted by flexible electronic devices, among which artificial nociceptors for pain perception are considered essential sensory devices. Recently, flexible diffusive memristors with volatile behavior are extensively studied to emulate biological synapses and neurons because of their rich threshold–switching dynamics, which are crucial for nociceptive functions. Herein, flexible diffusive memristors with an Ag/TaO_1.8/TaO_2.7/TaO_1.8/Ag (ATTTA) structure are fabricated at room temperature, demonstrating a high switching ratio of 107, an ultra-fast turn-on speed of 40 ns, a long endurance up to 104 sweep cycles, low positive and negative threshold variation rates (6.7%/7.8%) for 50 devices, a good thermal stability at an 85 °C measurement temperature, and a high flexibility under an 8 mm bending radius. These high performances are attributed to the oxygen-rich TaO_2.7 layer, which can prevent the excessive migration of Ag atoms. Moreover, multiple biological nociceptor functions, including threshold firing, no adaptation, and sensitization, are successfully emulated in the flexible ATTTA diffusive memristor. Accordingly, the human–skin nociceptive system is successfully emulated by integrating ATTTA diffusive memristor array with force–sensing resistors (FSRs), which enables stereoscopic injury perception of inhomogeneous stimuli.