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Computing with Charged Colloids?
Speaker Prof. René van Roij, Utrecht University
Date 13 May 2024 (Monday)
Time 15:00 - 16:00
Venue Room 4502, Academic Building, HKUST (Lifts 25-26)

In this talk we will discuss very recent work [1] in which we theoretically and experimentally show that a tapered microfluidic channel filled with an aqueous nearly close-packed dispersion of colloidal charged spheres is a memristor, i.e. a resistor with memory. We show that applying a positive (negative) voltage over the channel increases (decreases) the conductance of the channel by a mechanisms that involves voltage-induced accumulation (depletion) of salt in the channel [2] on a time scale τ proportional to the square of the channel length [3]. Upon applying a train of positive (negative) voltage pulses, with pulse durations τ/8 and representing a binary “1” (“0”), we map a binary bit string on a channel conductance, which offers opportunities for reservoir computing -we give a proof of principle for the case of recognizing hand-written digits [1]. If time permits we will also discuss ongoing work along these lines on pressure-effects [4] and chemical signalling [5].

[1] T.M. Kamsma, J. Kim, K. Kim, W.Q. Boon, C. Spitoni, J. Park, and R. van Roij, Brain-inspired computing with fluidic iontronic nanochannels, PNAS 121, e23202242121 (2024).
[2] W.Q. Boon, T. Veenstra, M. Dijkstra, and R. van Roij, Pressure-sensitive ion conduction in a conical channel: optimal pressure and geometry, Physics of Fluids 34, 101701 (2022).
[3] T.M. Kamsma, W.Q. Boon, T. ter Rele, C. Spitoni, and R. van Roij, Iontronic Neuromorphic Signaling with Conical Microfluidic Memristors, Phys. Rev. Lett. 130, 268401 (2024).
[4] A. Barnaveli, T.M. Kamsma, W.Q. Boon, and R. van Roij, Pressure-gated microfluidic memristor for pulsatile information processing, arXiv 2404.15006.
[5] T.M. Kamsma, M. Klop, W.Q. Boon, C. Spitoni, and R. van Roij, manuscript in preparation.

Please contact phweb@ust.hk should you have questions about the talk.