EGaIn tube memristors offer reliable switching on a biological time scale

Memristive devices have been considered promising candidates for nature-inspired computing and in-memory information processing. However, experimental devices developed to date typically show significant variability and function at different time scales than biological neurons and synapses. This study presents a new kind of memristive device comprised of liquid-metal eutectic gallium indium (EGaIn) contained within a mm-scale tube that operates via a bulk, voltage-dependent switching mechanism and exhibits distinct unipolar resistive switching characteristics that occur on a biological time scale (tens of milliseconds). The switching mechanism involves voltage-controlled growth and dissolution of an oxide layer on the surface of the liquid metal in contact with an aqueous electrolyte. Through comprehensive measurements on many devices, we observed remarkably consistent cycle-to-cycle behavior and uniformity in the voltage-controlled memristance. We present our findings, which also include an experimental demonstration of logic gates utilizing EGaIn tube memristors. Furthermore, we observe both accelerated and decelerated switching behaviors and identify signatures indicative of a fractional dynamic response.