Disordered hyperuniformity, memory and information coding in droplet chains.

Disordered materials with suppressed large-scale density fluctuations (as compared, e.g., to equilibrium liquids or glasses), so-called disordered hyperuniform (DH) materials, are known to exhibit unique mechanical, optical and transport properties. To date, DH structures were demonstrated only in 2D and 3D. Here, for the first time, we report a granular quasi-1D system spontaneously developing DH spatiotemporal patterns. We apply microfluidics to generate chains of droplets rearranging in a stationary external co-flow and find that the rearrangements are hyperuniform in time and space. We find that the suppression of the fluctuations is linked to the correlations between subsequent rearrangements - a manifestation of system ‘memory’ - and associated with strain propagation along the chain. We develop a model which predicts that the length of the memory is set by the relaxation time and the frequency of droplet generation, in agreement with observations. Finally, we also discuss how the generated structures could be used to encode information about the content of the droplets, opening way to new types of microfluidic assays for high-throughput screening appliactions.