Bioinspired Flexible, Dual‐Modulation Synaptic Transistors toward Artificial Visual Memory Systems

Abstract

A prominent challenge for artificial synaptic devices toward artificial perception systems is hardware redundancy, which demands neuromorphic devices that integrate both sensing and processing functions. Inspired by the biological visual and nervous systems, a novel flexible, dual‐modulation synaptic field‐effect transistor (SFET) is demonstrated in this work. The flexible SFET is constructed with zinc oxide nanowires and sodium alginate, which acts as the semiconductor layer and the gate dielectric, respectively. An excitatory postsynaptic current in this artificial synapse can be triggered by both electrical and ultraviolet stimuli as presynaptic spikes as a result of the electric double layer effect and the photoelectric effect. More importantly, through the co‐modulation of light and electric stimuli, the memory level of the artificial synapses can be tuned based on the transformation between short‐term plasticity and long‐term plasticity initiated by the gate voltage. Different voltages can modulate the memory retention levels of the optical inputs similar to the function of the optic nerve system. The underlying mechanisms for the SFET are investigated using Fourier transform infrared spectroscopy, photoluminescence, and X‐ray photoelectron spectroscopy. Overall, the devices provide a novel idea to mimic visual memory, showing a promising strategy for future electronic eyes.

Recent Progress in Optoelectronic Synapses for Artificial Visual‐Perception System

“…Reproduced with permission. [ 34 ] Copyright 2019, American Chemical Society. j) Schematic illustration of the Schottky barrier between Au and LSNO under illumination (top) and after illumination (bottom).…”

“…Sun et al demonstrated a flexible optoelectronic synapse based on the ZnO nanowires and sodium alginate (SA) in the ionic‐gated transistor geometry. [ 34 ] The photoinduced oxygen releasing and PPC behavior in ZnO nanowire gave rise to the synaptic plasticity. The EPSC could be triggered by both electric pulses through the gate electrode and light stimuli (Figure 5i).…”

Evolution of Bio‐Inspired Artificial Synapses: Materials, Structures, and Mechanisms

“…Light‐, gas‐, and pressure‐sensitive ASs are developed recently either in a single device or in an integrated system with separated sensors. [ 119–126 ]…”

“…Light-, gas-, and pressure-sensitive ASs are developed recently either in a single device or in an integrated system with separated sensors. [119][120][121][122][123][124][125][126] A flexible conformable AS was demonstrated as a human olfactory system to simulate human organ-damage memory behavior toward toxic NO 2 gas (Figure 10a). [119] This gas-sensitive FET-based AS was fabricated using poly[4-(4,4-dihexadecyl-4H-cyclopenta-[1,2-b:5,4-b0]dithiophen-2-yl)-alt- [1,2,5] thiadiazolo [3,4-c]pyridine] (PCDTPT) thin film on a freestanding PVA substrate.…”

Recent Process of Flexible Transistor‐Structured Memory

“…They can integrate optical and electric synergetic neuromorphism, and therefore can be used to simulate retinal function. Photonic TSAS devices based on CsPbBr 3 perovskite quantum dots (QDs), [ 142 ] MoS 2 /PTCDA, [ 143 ] MoS 2 /ZnO hybrid heterojunctions, [ 144 ] and zinc oxide nanowires (ZnO NWs)/sodium alginate (SA) [ 145 ] have been reported.…”