Active Mixing of Disparate Inks for Multimaterial 3D Printing

3D printing of multimaterial parts relies upon efficient mixing of the ink components and a rapid response to composition changes. However, at low Reynolds numbers and large Peclet numbers, mixing disparate viscosity and density inks poses a challenge. In this study, the performance of active micromixers for disparate non-Newtonian inks is evaluated using both experiments and computational fluid dynamics simulations. The mixing efficiencies are compared with scaling relationships for active micromixers. Using detailed simulation results, multiple factors are identified that can impact the micromixer response time during a composition change. Lastly, an active micromixer is proposed and evaluated to efficiently mix arbitrary multimaterial ink compositions and produce fine composition gradients within printed parts.