Dual-gate electrochemical synaptic transistor for tunable frequency-selective signal processing

Artificial synaptic transistors represent promising building blocks for time- and frequency-domain signal processing. However, most electrolyte-gated devices are constrained by fixed synaptic plasticity and frequency responses, limiting their functional versatility. Herein, we demonstrate a dual-gate MoS2 synaptic transistor, with the second gate serving as an independent control terminal to achieve gate-tunable frequency-selective characteristics. The device exhibits essential synaptic functionalities, including excitatory postsynaptic currents (EPSCs), paired-pulse facilitation (PPF), and spike-frequency-dependent plasticity (SFDP). It achieves a millivolt-level gate sensitivity (down to 5 mV) and an ultralow energy consumption of ∼187 fJ per synaptic event. Notably, the frequency-dependent response of the transistor can be dynamically modulated via the dual-gate configuration, where the second gate enables the cutoff frequency (fc) to be tuned from 10.79 to 12.8 Hz, providing a tunable window for high-pass signal processing. Image-processing simulations confirm that tuning the cutoff frequency allows selective enhancement of high-frequency features (e.g., edges and textures). Collectively, these findings illustrate that a dual-gate MoS2 synaptic transistor can integrate short-term plasticity, tunable frequency-selective processing, and low energy consumption into a compact platform, holding significant promise for advanced neuromorphic signal processing.