# Memristor Synapse—A Device-Level Critical Review

## TL;DR

This paper reviews memristor synapses as a promising technology for neuromorphic computing, focusing on their ability to mimic brain-like plasticity and their potential in healthcare applications.

## Contribution

The paper provides a device-level critical review and highlights the use of optoelectronic synapses based on 2D materials for enhanced brain-like plasticity.

## Key findings

- Memristor synapses enable ultra-high-density integration for large-scale machine learning.
- Optical stimulation of 2D material-based synapses broadens memristor controllability.
- Applications include pattern recognition and healthcare technologies like retinal implants.

## Abstract

The memristor has long been known as a nonvolatile memory technology alternative and has recently been explored for neuromorphic computing, owing to its capability to mimic the synaptic plasticity of the human brain. The architecture of a memristor synapse device allows ultra-high-density integration by internetworking with crossbar arrays, which benefits large-scale training and learning using advanced machine-learning algorithms. In this review, we present a statistical analysis of neuromorphic computing device publications from 2018 to 2025, focusing on various memristive systems. Furthermore, we provide a device-level perspective on biomimetic properties in hardware neural networks such as short-term plasticity (STP), long-term plasticity (LTP), spike timing-dependent plasticity (STDP), and spike rate-dependent plasticity (SRDP). Herein, we highlight the utilization of optoelectronic synapses based on 2D materials driven by a sequence of optical stimuli to mimic the plasticity of the human brain, further broadening the scope of memristor controllability by optical stimulation. We also highlight practical applications ranging from MNIST dataset recognition to hardware-based pattern recognition and explore future directions for memristor synapses in healthcare, including artificial cognitive retinal implants, vital organ interfaces, artificial vision systems, and physiological signal anomaly detection.