Fabrication of Low-Cost, High-Resolution Open Capillary Microfluidics towards Self-Sustaining, Long-Term Hydration of Engineered Living Materials

Engineered living materials (ELMs) are an emerging class of biohybrid materials that have shown great promise with advanced capabilities unachievable by conventional materials. However, application of ELMs outside of the laboratory has been limited due to the need for periodic media replenishment or complete media immersion. We herein demonstrated the integration of capillary microfluidics for the autonomous and pump-free hydration of ELM hydrogels. We optimized 3D printing parameters, including exposure time and build plate lift and retract distances, to obtain microchannel dimensions capable of spontaneous capillary flow using a low-cost liquid crystal display stereolithographic apparatus (LCD-SLA) 3D printer and two hydrogel resins that are suitable for ELMs. Microchannel dimensions were accurate with ≤ 10% deviation between designed and measured widths and precise with coefficients of variation (CVs) <5% for microchannels ≥ 206.4 μm. We demonstrated proof-of-concept spontaneous capillary flow in 3D printed microfluidic devices using dye-incorporated lysogeny broth (LB). Snapshots of the devices captured up to 24 hours showed the diffusion of dye-incorporated LB throughout the bulk material. Through this proof-of-concept study, we have showcased the feasibility of integrating capillary microfluidics with ELMs for the autonomous and pump-free flow of fluids towards self-sustaining and long-term hydration.