Low-Voltage Oxide-Based Synaptic Transistors for Spiking Humidity Detection

In order to obtain higher humidity sensitivity, shorter response/recover time, and lower energy consumption, we investigate the dynamic humidity sensing characteristics of indium-zinc-oxide (IZO)-based synaptic transistors with graphene oxide/chitosan composite electrolyte films as the gate dielectrics. Here, the short-term synaptic plasticity parameters, such as excitatory post-synaptic current, paired-pulse facilitation index, and high-pass filtering coefficient, were used for quantitative characterization of the relative humidity. The spiking humidity response time and energy consumption of such synaptic transistors are estimated to be 30 ms and 2.2 nJ, respectively. At the same time, a model based on the humidity-dependent proton gating and the adsorption of water molecules at the IZO channel surface is proposed.