An Artificial Olfactory System Based on Synaptic Transistors for Precepting Hazardous Gas to Simulate Organ Injury.

Recent advances in artificial olfactory systems have attracted significant attention for their potential applications in humanoid robots and intelligent nasal devices capable of identifying objects and sensing hazards; however, the memory function is absent in traditional gas sensors, which is crucial to assess the long-term exposure risks. Meanwhile, due to the high operation temperature requirement, the gas sensors are usually difficult to integrate with the synaptic devices to form artificial olfactory systems. Here, we propose a novel artificial olfactory synaptic device to obtain and memorize formaldehyde information. The device is composed of an ion gel synaptic transistor integrated with a Ag-ZnO gas sensor, which can simulate the adverse effects of formaldehyde exposure to the human body and make an early warning. The Ag-ZnO gas sensor can detect and recognize different concentrations of formaldehyde as the chemiresistive signal at room temperature with ultraviolet irradiation instead of at high temperatures. The formaldehyde-induced resistive changes are transmitted to the gate voltage of the synaptic transistor, modulating the channel conductance to generate varying postsynaptic currents and to store gas information to realize the memory function. In addition, the postsynaptic current data of different concentrations can be imported into a support vector machine (SVM) for accurate identification, and early warning of different concentrations can be realized through the system. This bionic olfactory system provides a promising strategy for the development of advanced artificial intelligence and danger warnings.