Chemically Regulated Conical Channel Synapse for Neuromorphic and Sensing Applications

TL;DR

This paper demonstrates how a chemically regulated microfluidic channel can emulate key synaptic features such as plasticity and signal detection, advancing fluidic iontronics for neuromorphic applications.

Contribution

It introduces a novel model of a conical microfluidic channel that captures complex synaptic behaviors through coupled chemical and electrical dynamics.

Findings

Emulation of short- and long-term synaptic plasticity.

Implementation of chemical-electrical spike-timing-dependent plasticity.

Demonstration of chemical-electrical AND logic gate behavior.

Abstract

Fluidic iontronics offer a unique capability for emulating the chemical processes found in neurons. We extract multiple distinct chemically regulated synaptic features from an experimentally accessible conical microfluidic channel carrying functionalized surface groups, using finite-element calculations of continuum transport equations. By modeling a Langmuir-type surface reaction on the channel wall we couple fast voltage-induced volumetric salt accumulation with a long-term channel surface charge modulation by means of fast charging and slow discharging. These nonlinear charging dynamics emerge across several orders of magnitude of reaction rates and equilibria, and are understood through an analytic approximation rooted in first-principles. We show how short-and long-term potentiation and depression, frequency-dependent plasticity, and chemical-electrical signal spike-timing dependence and coincidence detection (acting like a chemical-electrical AND logic gate), akin to the NMDA mechanism for Hebbian learning in biological synapses, can all be emulated.