High‐Precision Stereolithography of Biomicrofluidic Devices

Abstract

Stereolithography (SL) is emerging as an attractive alternative to soft lithography for fabricating microfluidic devices due to its low cost and high design efficiency. Low molecular weight poly(ethylene glycol)diacrylate (MW = 258) (PEG-DA-258) has been used for SL 3D-printing of biocompatible microdevices at submillimeter resolution. However, 3D-printing resins that simultaneously feature high transparency, high biocompatibility, and high resolution are still lacking. It is found that photosensitizer isopropyl thioxanthone can, in a concentration-dependent manner, increase the absorbance of the resin (containing PEG-DA-258 and photoinitator Irgacure-819) by over an order of magnitude. This increase in absorbance allows for SL printing of microdevices at sub pixel resolution with commercially available desktop printers and without compromising transparency or biocompatibility. The assembly-free, rapid (<15 h) 3D-printing of a variety of complex 3D microfluidic devices such as a 3D-fluid router, a passive chaotic micromixer, an active micro-mixer with pneumatic microvalves, and high-aspect ratio (37:1) microchannels of single pixel width is demonstrated. These manufacturing capabilities are unavailable in conventional microfluidic rapid prototyping techniques. The low absorption of small hydrophobic molecules and microfluidic labeling of cultured mammalian cells in 3D-printed PEG-DA-258 microdevices is demonstrated, indicating the potential of PEG-DA-based fabrication of cell-based assays, drug discovery, and organ-on-chip platforms.

Hybrid negative enrichment of circulating tumor cells from whole blood in a 3D-printed monolithic device

“…Post-filtration of leuko-depleted blood within the same device allowed us to retain all nucleated cells, including residual WBCs on a detachable membrane filter, which enabled effortless removal of viable tumor cells off the chip for downstream assays. With the demonstrated feasibility in processing clinical samples, we envision that finer microscale features that will be enabled by ongoing advances in additive manufacturing 62 will further improve the performance and ultimately allow our scalable technique to be used for label-free negative depletion of CTCs from whole blood in clinical settings.…”

3D Printing of Inertial Microfluidic Devices

“…To address these inadequacies, we have developed a robust protocol for large-scale manufacturing of inertial microfluidic systems. Thanks to the capabilities of DLP and SLA 3D printing 42,43 , we have printed a wide range of microchannels with different geometries, capable of performing particle and cell focusing for various Reynolds numbers (Re). The approach makes the use of a double-coated pressure-sensitive adhesive tape that perfectly binds open 3D-printed microchannels with optically transparent acrylic sheets, producing a leakage-free interface for inertial microfluidic applications.…”

Facile Fabrication of Microfluidic Chips for 3D Hydrodynamic Focusing and Wet Spinning of Polymeric Fibers

“…However, the channel geometry [27], produced in a layer-by-layer fashion, may affect the flow behavior and therewith the resulting fiber morphology, similar to what was shown by using chevrons [28]. Meanwhile, this effect can be further provoked by the presence of pixelated channel walls [17,23,24]. Although multiphoton lithography solves many of these critical aspects [7] and gives resolutions up to a few hundred nanometers, the equipment cost is too prohibitive for a steady transition to industrial settings.…”

“…Recent advances in additive manufacturing have allowed rapid prototyping of devices with high versatility and precision [17]. While conventional fused deposition modeling (FDM) 3D printers fail to produce microfluidic coaxial reactors due to the inherent x-y low resolution [18][19][20][21], digital light processing (DLP) and masked stereolithography (MSLA) printers have recently shown the possibility to produce transparent microfluidic devices with the single-pixel resolution higher than 47 µm [22][23][24][25][26][27]. However, the channel geometry [27], produced in a layer-by-layer fashion, may affect the flow behavior and therewith the resulting fiber morphology, similar to what was shown by using chevrons [28].…”