Transparent and biocompatible In₂O₃ artificial synapses with lactose–citric acid electrolyte for neuromorphic computing

Electrolyte-gated synaptic transistors are promising for artificial neural morphological devices. However, few literatures have been reported regarding the manufacturing of electrolyte-gated synaptic transistors with low cost and biocompatible components. Here, the fully transparent synaptic transistors based on water-induced In₂O₃ thin films have been integrated by sol–gel method at low temperature, and lactose dissolved in citric acid solution is used as the gate electrolyte. The migration of the ions at the interface plays a crucial role in the potentiation and depression of the synaptic weight. In this work, the biological synaptic functions, including excitatory postsynaptic current, paired-pulse facilitation, high-pass filtering characteristics, short-term memory, and long-term memory, are mimicked. Meanwhile, based on the potentiation/depression behaviors of the synaptic transistor, a three-layer artificial neural network is applied for pattern recognition, and the recognition accuracy is as high as 94.6%. This study offers a possibility to realize fully transparent synaptic devices with biocompatible components at low temperature.