Unveiling the capabilities of bipolar conical channels in neuromorphic iontronics

Abstract

We quantitatively explain the diodic and memristive properties of conical ion channels with bipolar surface charges. A modelled iontronic circuit of these channels exhibits neuronal spiking with membrane potentials comparable to mammalian values.

Advanced iontronic spiking modes with multiscale diffusive dynamics in a fluidic circuit

“…In this work we expand upon the previously reported features of neuronal spiking in fluidic iontronics [15,29]. By building upon a previously reported iontronic circuit [15] and a physical description of the dynamical conductance of conical channels with a bipolar (BP) surface charge [39], i.e. positive at the base and negative at the tip, we can unlock various new forms of spiking dynamics.…”

“…Conical fluidic ion channels act as iontronic volatile memristors [40] and are being investigated as possible candidates for synaptic devices [41] and spiking circuits [15,39]. Using theoretical models that quantitatively explain the memristive behaviour of conical channels, it was shown that HH-inspired fluidic circuits containing three conical channels and a capacitor exhibit tonic and phasic spiking [15,39].…”

“…Conical fluidic ion channels act as iontronic volatile memristors [40] and are being investigated as possible candidates for synaptic devices [41] and spiking circuits [15,39]. Using theoretical models that quantitatively explain the memristive behaviour of conical channels, it was shown that HH-inspired fluidic circuits containing three conical channels and a capacitor exhibit tonic and phasic spiking [15,39]. This modelled circuit was originally composed of conical ion channels with a homogeneous unipolar (UP) surface charge Two short channels of equal length L ± = 1 µm with fast dynamics on a typical timescale τ ± ≈ 0.042 ms and conductances g ± (t), a longer channel of length Ls = 15 µm with slower dynamics on a typical timescale τs ≈ 9.4 ms and conductance gs(t), and an even longer channel of length Lss = 90 µm with conductance gss(t) and the slowest dynamics over a typical timescale τss ≈ 338 ms.…”

“…Adapted figure with permission from [15], Copyright (2023) by the American Physical Society. [15] and was later modified by replacing the UP channels with conical channels carrying a BP inhomogeneous surface charge [39], positive at the base and negative at the tip. BP fluidic channels and (Janus) membranes have long drawn great interest as current rectifiers [42][43][44][45][46][47] for applications in e.g.…”

Synaptical Tunability of Multipore Nanofluidic Memristors

“…Ion-based neuromorphic devices have attracted wide interest both in fundamental and applied chemistry audiences. − The basic building block of neuromorphic signal processing is the memristor. − Here, we describe a multipore nanofluidic memristor with conical pores on a polymeric substrate that shows a wide range of ionic conduction properties, including current rectification. This electrochemical memory resistor exhibits a robust history-dependent behavior based on the electrical interaction between the functionalized charges on the conical pore surface and the nanoconfined ionic solution. − We show that the memristor active response can be switched in current and polarity by pH control, which provides additional functionality for chemical computation and neuromorphic applications.…”