Fabrication of double-sided microfluidic structures via 3D printed transfer molding

Abstract

In this work, we demonstrate the use of 3D printed molds for rapidly fabricating multi-layer PDMS-based microfluidic devices. Because 3D printing allows for versatile and cost-effective mold construction, it can produce significantly more varied features than those generated by soft lithography. We first discuss adaptations to single-layer 3D molding, including a glass bonding technique to compensate for the limitations of surface roughness and 0.55mm built-in inlet and outlet ports to eliminate fabrication steps. Next we introduce two-sided fabrication methods, facilitated by novel built-in alignment marks. These techniques allow the construction of formerly difficult to achieve features such as non-planar 350 urn membranes, used to fabricate a single-layer membrane valve which actuates at 200kPa, and single-layer microfluidic vias, used to generate 3D flow patterns. Lastly, we demonstrate an intra-layer bonding technique where a custom 3D printed stamp selectively applies liquid PDMS adhesive, compensating for surface roughness while preventing channel clogging. Together, these techniques enable the rapid assembly of multi-layer PDMS-based microfluidic devices, combining the versatility and speed of emerging 3D printing technology with the known mechanical and biological properties ofPDMS favored by microfluidic researchers.