Light-Programmed, Optically Multiplexed Memory Lifetimes in a Monolithic Ionogel

Biological synapses encode time across a hierarchy of relaxation timescales, allowing neural circuits to process information over multiple temporal windows. Reproducing such spatially distributed, multi-timescale memory within a single continuous medium remains difficult: electronic synaptic devices require segmented electrodes to address distinct states, and in an ionically continuous ion gel, spatially separated regions cannot be read independently because the shared medium couples them. We overcome this by encoding memory optically — as color — and programming it spatially with light. Electrochromic ionogels were prepared by 365 nm DMD-based maskless UV lithography of a photocurable PEGDA precursor containing an ionic liquid and a molecularly tailored electrochromic species. The active molecule was synthesized in concert with the network so that target colored states emerge at specific crosslink densities: the local UV dose sets the crosslink density and the resulting molecular organization of the active species, which together determine both the colored state and its memory lifetime under globally applied stimulation. In this way, multiple distinct colored states — each with a different retention time — are accessed within a single fixed composition. Notably, the recovery timescale is not limited by ionic transport, which relaxes orders of magnitude faster than memory recovery, but is instead governed by the UV-defined molecular state. By co-designing the molecule and the photopatterned network, both color and memory lifetime become local, lithographically written material properties of a single, compositionally identical ionogel, read out in parallel by optical imaging without any electrode segmentation. This allows many memory states of different timescales to coexist and be addressed within one continuous medium, offering a route to multiplexed neuromorphic architectures, multilevel optical memory, and temporal information processing.