Development of 3D printed microchips with encapsulated channels as miniaturized separation devices for bioanalysis

3D printing has emerged as an attractive alternative for the fabrication of microfluidic devices offering the ability for rapid prototyping and a high degree of customization, in contrast to conventional microfabrication techniques. Despite its potential, the size of internal features (such as microfluidic channels) has been limited to larger cross-sectional areas and shorter lengths. Advances in 3D printing technology and the development of custom resins have allowed for smaller features to be obtained, moving the field closer to genuine microfluidic devices. However, not all researchers can readily perform the customization or resin development required.

In this work, we obtained channels with smaller cross-sections (∼100-200 μm) and longer channel lengths (up to 96 mm) using a commercial printer and resin, by optimizing several printing parameters as well as aspects of the microfluidic design. A chip array and custom 3D printed manifold was used to develop a workflow for high throughput post-processing, enabling facile removal of uncured resin from enclosed channels. Using a rectangular channel geometry, a layer height of 50 μm, and a single layer cover, channels with specified dimensions of 150 × 150 μm and 6 mm total length were obtained with a high success rate (>98 %). Channels up to 96 mm could be printed using dimensions of 200 × 200 μm. The potential for these microchips for the pre-concentration and separation of proteins was also demonstrated, by fabricating polyacrylamide separation gels within the channels.

This work presents an alternative workflow for fabrication of enclosed channels that does not rely on the use of custom printers or resins. Implementation of this workflow with pre-existing 3D printing technology is expected to allow future research progress facilitating smaller channel dimensions of longer lengths more readily. If coupled with emerging 3D printing technology, this could open the door for the development of truly microfluidic devices for bioanalysis and point-of-care devices in healthcare settings.