(155e) Masked Stereolithography Printing for Rapid Prototyping of Microfluidic Systems with Embedded Functional Components

3D printing microfluidic structures for prototyping has gained a lot of attention due to several advantages such as fast production, cost-effectiveness, and versatility over traditional photolithography and PDMS mold-based microfabrication techniques. We report the application of masked stereolithography (MSLA) 3D printing approach with our multi-material UV curable resin formulation to enable single-step fabrication of intricate and functional microfluidic chips. The hybrid technique utilizes both UV curable commercially available resins and our custom resin formulations incorporating either high molecular weight Polyethylene glycol diacrylate (700 & 3400) or Ethylene glycol polyether acrylate (EGPEA) as the monomer unit to achieve sub-50 micron sized positive features with tunable mechanical and optical properties. We analyze the range of achievable optical and mechanical characteristics as a function of varying monomer composition in our custom resins. We also determine optimal resin composition and printing parameters to directly print multi-level embedded rectangular microfluidic channels (eliminating the need for chip bonding steps). By incorporating multiple resins with different mechanical properties, we were able to achieve spatial control over the stiffness of the cured resin enabling us to incorporate both flexible and rigid components within a single 3D printed structure.

We demonstrate the utility of this technique by 3D printing an integrated pressure-actuated diaphragm valve (with flexible cured resin) in an otherwise rigid and clear microfluidic device that can be fabricated in a one-step process from a single CAD file. We also present a step-by-step guide and tutorial that will enable researchers to use their commercial desktop MSLA 3D printers to print functional microfluidic devices. The versatility of our fabrication technique enables one to go from an “idea stage” to a “fabricated microfluidic chip” within ~hours as opposed to traditional clean room-based microfabrication (~days), which could drastically lower the barrier to entry and greatly accelerate lab-on-a-chip research.