Project 11

OPTIMIZATION OF POST CURING FOR SLA 3D PRINTED PDMS MOLDS FOR MICROFLUIDICS

(dr. Tom Roussel, UofL BIOMEMS LAB)

Polydimethylsiloxane (PDMS) is a hydrophobic, silicon-based organic polymer that is a popular substrate for rapid manufacturing of experimental platforms in bioengineering and for experimental soft-lithography to study microfluidics. In many cases, microfabrication techniques are used to create negative molds of channels. Geometry is created on silicon wafers, and PDMS is poured over these geometric features allowed to cure. When peeled off the substrate, fine details remain in the PDMS. To further increase the rapidity of iterative design, and to push the limits of creating 3D microfluidics, an additive manufacturing technique called stereolithography is used in “SLA” printers is being adopted for creating the casting molds for PDMS. Modern 8K resolution images on these SLA printers can push the line resolution into the tens of microns. Unfortunately, the chemical resins use to create SLA parts chemically interact with PDMS which often can delay or even prevent complete curing, rendering the molds useless. Therefore, post-processing steps (washing, extended UV curing, etc.) are often necessary to prevent this interaction. Additional treatments such as parylene coating also are used to prevent the PDMS to Resin interaction and allow the PDMS to fully cure.

This project will explore optimization of the use of SLA molds for curing PDMS microchannels. Since the resolution of higher resolution SLA printers are less than 100 µm, studies to push the limits of creating internal microchannels in SLA geometry (free of the planar limits of PDMS) will also be explored.