(492b) Architecting Soft Materials Using Fluidic Gates: A Practical Analogy to Boolean Logic

Soft materials often derive their functional properties from the hierarchical arrangement of disparate phases. While hierarchy can develop spontaneously after certain systems are perturbed, self-assembled structures are rather limited to particular geometric configurations, such as the fractal aggregates found in colloidal gels and the tortuous pores found in bijels. In this talk, we present a continuous processing scheme that uses networks of closed fluidic channels to assemble disparate materials into voxelated, designer patterns. Three basic elements comprise the fluidic networks: (a) T – junctions which combine flows, (b) T – junctions which split flows, and (c) corners which rotate flow. These elements faithfully contour laminar streamlines, which in turn pattern advecting species. To model the patterns, we cast the three flow elements as a Boolean-logic inspired gates. Networks are formed by combining flow elements in modular sequences, as one would combine “AND”, “OR”, and “NOT” gates to form a Boolean circuit. The formalism is illustrated using a library of experiments with model viscoplastic materials. Generally, combining elements in series produce symmetric patterns, while combining elements in parallel produce asymmetric patterns. The patterns are quantitatively predicted using a custom MATLAB Simulink package, which notably does not require any detailed rendering of the actual channels. Within appropriate operating and rheological constraints, the architectures assembled are determined by the contours of the device rather than the composition of the constituents. We highlight the utility of this geometrically dictated process by briefly describing how advective assembly has been used to structure in two different applications: [1] patterning hydrogel cross-linking density to program shape actuation, [2] intensifying emulsification of high-viscosity ratio systems. This work exemplifies advective processing’s broad potential to encode useful soft material hierarchy through modular flows.

[1] Bayles, Pleij, Hofmann, Hauf, Tervoort, Vermant. ACS Applied Materials and Interfaces, 2022, DOI: 10.1021/acsami.2c02069

[2] Hofmann, Bayles, Vermant. AIChE Jourrnal, 2021. DOI: 10.1002/aic.17192