Rapid Prototyping of Microfluidic Devices with Stereolithographic 3D Printing.

3D printing has become a prevalent technology in many fields such as manufacturing, architecture, and electronics. This additive manufacturing technique is also widely used for biomedical research and clinical applications to prototype or assemble biomedical devices and tools. 3D printing-based strategies for biocompatible materials offer greater design flexibility, enhanced versatility, and faster results than traditional fabrication techniques, advantages that could be especially beneficial to the development of microfluidic chips. The ability to simply and efficiently produce new chip molds from computer aided design (CAD) models would significantly transform the development process and expand its accessibility by removing the need for more complex and expensive lithography methods. However, with standard processing strategies, the use of 3D printed molds for casting functioning chips is limited by the poor quality of prints achievable with widely available 3D printers. To mitigate this issue and facilitate rapid microfluidic device prototyping, we have developed a simple procedure to print microfluidic molds using a stereolithographic (SLA) printer and produce functional polydimethylsiloxane (PDMS) microfluidic chips with height and width feature dimensions as low as 75 μm. Molds printed using a commercially available liquid photopolymer-based resin and processed using our strategy exhibited high dimensional fidelity to intended designs and significantly reduced average surface roughness (< 3 μm). Here, we describe a streamlined post-print processing workflow for SLA molds and its efficacy in reducing surface roughness while preserving dimensional fidelity and then demonstrate its utility by prototyping and optimizing a microfluidic extracellular vesicle (EV)-exchange platform.