Paper Number
AC13 

Session
Additive Manufacturing and Composites

Title
Structuring multi-material 3D printing filaments using fluidic gates: A practical analogy to Boolean logic

Presentation Date and Time
October 12, 2022 (Wednesday) 4:05

Track / Room
Track 7 / Ontario

Authors (Click on name to view author profile)

  1. Bayles, Alexandra V. (University of Delaware, Chemical and Biomolecular Engineering)
  2. Pleij, Tazio (ETH Zürich, Materials)
  3. Murdock, Matthew N. (University of Delaware, Chemical and Biomolecular)
  4. Vermant, Jan (ETH Zürich, Materials)

Author and Affiliation Lines (in printed abstract book)
Alexandra V. Bayles1, Tazio Pleij2, Matthew N. Murdock1 and Jan Vermant2
1Chemical and Biomolecular Engineering, University of Delaware, Newark, dE, DE 19716; 2Materials, ETH Zürich, Zürich, Switzerland

Speaker / Presenter 
Bayles, Alexandra V.

Keywords
experimental methods; additive manufacturing; emulsions

Text of Abstract
Materials often derive their functional properties from the hierarchical arrangement of disparate materials. Hierarchical architectures can be readily constructed using additive manufacturing by swapping nozzles and inks over the course of a print. However, practical constraints limit the geometric complexity, length scales, and materials employed. To expand operating windows and throughputs of existing methods, we designed serpentine, millifluidic devices to assemble advecting materials into voxelated patterns. The `advective assembly’ devices include three basic elements: (1) T – junctions which combine flows, (2) T – junctions which split flows, and (3) corners which rotate flow. Serpentine geometries are formed by combining flow elements in modular sequences, as one would combine “AND”, “OR”, and “NOT” gates to form a Boolean circuit. The modeling formalism is realized in a library of experiments with model viscoplastic inks. 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 a detailed rendering of the actual channels. With this rational design framework in hand, we extrude precisely structured multi-material filaments, which can then be arranged into objects along a conventional 3D printing path. Preassembling the lower levels of hierarchy in flow circumvents intrinsic challenges in layer-by-layer deposition, including ensuring interlayer adhesion, discretizing complex morphologies, and tuning feature size without incurring large pressure drops. We highlight the utility of this geometrically dictated process by briefly describing how hierarchical filament 3D printing has been used to pattern hydrogel cross-linking density to program shape actuation [10.1021/acsami.2c02069]. Altogether, this work exemplifies advective assembly’s broad potential to encode useful soft material hierarchy using modular flows.