A Solution to the Clearance Problem of Sacrificial Material in 3D Printing of Microfluidic Devices

Abstract

3D-printing is poised to enable remarkable advances in a variety of fields, such as artificial muscles, prosthetics, biomedical diagnostics, biofuel cells, flexible electronics, and military logistics. The advantages of automated monolithic fabrication are particularly attractive for complex embedded microfluidics in a wide range of applications. However, before this promise can be fulfilled, the basic problem of removal of sacrificial material from embedded microchannels must be solved. The presented work is an experimental proof of principle of a novel technique for clearance of sacrificial material from embedded microchannels in 3D-printed microfluidics. The technique demonstrates consistent performance (~40–75% clearance) in microchannels with printed width of ~200 µm and above. The presented technique is thus an important enabling tool in achieving the promise of 3D printing in microfluidics and its wide range of applications.

Dimensional Fidelity and Orientation Effects of PolyJet Technology in 3D Printing of Negative Features for Microfluidic Applications

“…To systematically test the effect of baking on the core chip material, an experiment was conducted where samples of SUP706B ( in each group) were exposed to two different temperatures and the mass of each sample was measured before and after baking [ 21 ]. Melting, i.e., the transition from solid to a liquid, was not observed during heating.…”

“…Previous work [ 21 ] has shown that exposing the sacrificial material to 80 °C leads to the formation of microcavities. A clearance procedure [ 21 ] exploits that effect to allow the clearance solution to fill those microcavities and helps to dislodge the sacrificial material. Thus, baking chips at 80 °C for approximately 2–4 h is part of the standard clearance procedure [ 21 ].…”

“…A clearance procedure [ 21 ] exploits that effect to allow the clearance solution to fill those microcavities and helps to dislodge the sacrificial material. Thus, baking chips at 80 °C for approximately 2–4 h is part of the standard clearance procedure [ 21 ]. All measurements in this study were taken before and after baking the chips.…”

“…The trade-off is that since microfluidic channels are created as negative features in 3D-printed devices, it is necessary to solve the related problems, such as fidelity, consistency, and the removal of sacrificial material. We recently reported on a method [ 21 ] to solve the removal problem, specifically within the Stratasys PolyJet technology. Among 3D printing techniques, PolyJet is particularly significant as it combines high resolution, large print volume, ability to print soft resins, and the ability to print multiple resins at the same time in the same device.…”

“…Previous work indicated that PolyJet-printed material is not within the accuracy limits as claimed by the manufacturer [ 22 ]. Moreover, our previous work on the PolyJet sacrificial material clearance procedure established that the technology prints sacrificial material and resin features generally wider than planned [ 21 ]. This exposed a need for proper calibration, to allow for high-quality predictive engineering of such structures, while also exploring additional fabrication factors, such as design orientation in reference to the printing head axes.…”