Neuromorphic functions with a polyelectrolyte-confined fluidic memristor

Abstract

Reproducing ion channel–based neural functions with artificial fluidic systems has long been an aspirational goal for both neuromorphic computing and biomedical applications. In this study, neuromorphic functions were successfully accomplished with a polyelectrolyte-confined fluidic memristor (PFM), in which confined polyelectrolyte–ion interactions contributed to hysteretic ion transport, resulting in ion memory effects. Various electric pulse patterns were emulated by PFM with ultralow energy consumption. The fluidic property of PFM enabled the mimicking of chemical-regulated electric pulses. More importantly, chemical-electric signal transduction was implemented with a single PFM. With its structural similarity to ion channels, PFM is versatile and easily interfaces with biological systems, paving a way to building neuromorphic devices with advanced functions by introducing rich chemical designs.

Nanofluidics at the crossroads

“…• The recent development of ion-based, nanofluidic memristors paves the way for 'iontronics' -transporting, processing and storing information through the use of solvated ions in water 25,47,62 . These experiments already demonstrated the possibility of implementing some form of Hebbian learning 25 , a basic form of learning algorithm.…”

“…The conductance of both nanopores and nanoslit was found to vary by a factor around 50 when applying a voltage drop ∆V ∼ 0.5 V, consistent with the previous interpretations of voltage gating in terms of interaction confinement and ion pairs. This combination of non-linear response and memory is at the source of the ionic memristor 25,47 . In electronics, memristors are used as solid-state equivalents of biological synapses due to their tunable conductance and their ability to store information over long timescales 48 .…”

“…Notable examples include carbon nanotubes with pressure-modulated conductance, and all devices displaying ionic rectification, like nanofluidic diodes. In particular, these systems have been shown to behave as memristors -electronic devices with hysteretic conductance -when exposed to time-varying voltage 24,25,47,62 . A no-table trait of such systems is to display a pinched loop in their current-voltage characteristic when exposed to a voltage sweep, as shown for example on Fig.…”

Learning from the Brain: Bioinspired Nanofluidics

“…The other category is nanofluidic memristors, which are a class of nanofluidic devices whose ionic conductivity has memory for historical voltages. Under the application of different bias voltages, the nanofluidic memristors can realize the ion enrichment and ion depletion in nanoconfinements through the polarization of the EDL, the increase of the nanochannel numbers, the movement of the liquid–liquid interface, , or the adsorption and desorption of ions on the nanochannel’s inner surface, , thereby realizing voltage- and time-dependent nanochannel conductivity plasticity. One of the most representative mechanisms in nanofluidic memristors is the fast adsorption and slow desorption of ions due to the strong interactions with the nanochannel inner surface.…”

“…(h) Schematic of the chemosensitive polyelectrolyte-confined fluidic memristors and their electric pulse response under the stimulation of anions . Reproduced with permission from ref . Copyright 2023, American Association for the Advancement of Science.…”