In-situ transfer vat photopolymerization for transparent microfluidic device fabrication

Abstract

While vat photopolymerization has many advantages over soft lithography in fabricating microfluidic devices, including efficiency and shape complexity, it has difficulty achieving well-controlled micrometer-sized (smaller than 100 μm) channels in the layer building direction. The considerable light penetration depth of transparent resin leads to over-curing that inevitably cures the residual resin inside flow channels, causing clogs. In this paper, a 3D printing process — in-situ transfer vat photopolymerization is reported to solve this critical over-curing issue in fabricating microfluidic devices. We demonstrate microchannels with high Z-resolution (within 10 μm level) and high accuracy (within 2 μm level) using a general method with no requirements on liquid resins such as reduced transparency nor leads to a reduced fabrication speed. Compared with all other vat photopolymerization-based techniques specialized for microfluidic channel fabrication, our universal approach is compatible with commonly used 405 nm light sources and commercial photocurable resins. The process has been verified by multifunctional devices, including 3D serpentine microfluidic channels, microfluidic valves, and particle sorting devices. This work solves a critical barrier in 3D printing microfluidic channels using the high-speed vat photopolymerization process and broadens the material options. It also significantly advances vat photopolymerization’s use in applications requiring small gaps with high accuracy in the Z-direction.

Applied tutorial for the design and fabrication of biomicrofluidic devices by resin 3D printing

“…1). [24][25][26] For commercial resins, strategies to diminish resin cytotoxicity have started to emerge recently, [27][28][29][30] along with solutions addressing print resolution, [31][32][33][34][35][36] imaging compatibility, 33,[37][38][39] and surface modification and bonding. 40,41 Sifting through the plethora of literature for best practices can be challenging for researchers who are new to this rapidly growing field.…”

3D-Printing for Critical Sized Bone Defects: Current Concepts and Future Directions

“…Pore size plays a crucial role in promoting the attachment of cells onto the scaffold, as well as their migration into and proliferation within the construct. One of the most important benefits of 3D printing techniques is that they allow for precise control over architectural details, and therefore the determination of an optimal pore size or range is critical in the development of scaffolds of increasing scale and complexity [ 93 , 188 ]. Lim et al evaluated the effect of pore size on the in vivo efficacy of biphasic calcium scaffolds composed of HA and β-TCP in rabbit calvarial defects and found that larger pore sizes (1200–1400 µm) were associated with enhanced bone formation, although this effect disappeared at 8 weeks [ 189 ].…”

A Review on Modeling Cure Kinetics and Mechanisms of Photopolymerization

“…Its huge potential in the simple and fast production of materials with special properties leads to a wide range of potential applications [ 2 ]. Practical applications include, for instance, coatings [ 1 , 3 ], tissue engineering [ 4 , 5 ], photolithography [ 6 , 7 , 8 , 9 ], microfluidic device fabrication [ 10 , 11 ], 3D prototyping [ 12 , 13 , 14 , 15 ], and 4D bioprinting [ 16 , 17 ]. Significant characteristics of photopolymerization include the solvent-free formulation, ability to cure at ambient temperature conditions (which is especially important for heat-sensitive materials), and low energy consumption, as well as spatial and temporal control over the polymerization [ 1 ].…”