Printing Processes and Technologies

Figure 1: Different types of printing technologies

3D printing is a crucial tool for the developers of microfluidic devices. Not all 3D printing techniques are used by microfluidic developers. "the term “3D printing”—considered to be synonymous with “solid freeform fabrication”—refers to a family of additive-based manufacturing techniques. Importantly, not all 3D printing techniques are suitable for microfluidics. The most widely used 3D printing techniques with relevance to microfluidics are selective laser sintering" (Au, Anthony K, Wilson Huynh, Lisa F. Horowitz, and Albert Folch). The different methods of 3D printing in microfluidics include Fabrication by Stereolithography, Fabrication by Selective Laser Sintering, Fabrication by photo polymer inkjet printing, fabrication by fused deposition modeling, and fabrication by laminated object manufacturing. These different methods of 3D printing have different levels of resolution and automation.

New Technologies (Paige Liu)

Two of the factors driving innovation in 3D printing for microfluidics are channel size and resolution,¹.

Exploration into additive materials using other materials such as concrete and biomaterials has also been of interest².

There are also some new methods of 3D printing that are being developed.

High Resolution 3D Printing Using a Customized Resin and Photolithography Printer

Using an adapted stereolithography (SLA) printer and a series of custom-formulated resins, a lab was able to create microchannels at up to 18x20 um resolution³. This method has not been reproduced in literature and definitely has yet to be scaled up, but it holds promise for the future of 3D printing microfluidic circuits.

(Will include some figures of the channel dimensions for scale from the paper)

Additive Manufacturing of Biomaterials

Additive manufacturing using biomaterials is a hot topic due to the obvious impact it would have on the development and manufacture of medical devices such as stents, artificial joints, etc. One of the driving forces of advancing additive manufacturing techniques for the production of biomedical devices is to reduce manufacturing costs and allow for rapid prototyping capabilities with less waste. The high variances in geometry from biological system to biological system (e.g. person to person) creates further demand for 3D printing type technologies, as the designs are easily customized in contrast to traditional manufacturing techniques.

One of the main challenges that come from adapting AM to biomaterials is removing powder/ other support type materials from the final product. Generally, any loose material could be problematic in-vitro since there could be problems with biocompatibility in a scattered vs. a conhesive final product⁴. Other challenges include high initial costs on the research and development side.

Computed Axial Lithography (CAL)

--> can stick this under photopolymerization

(Some technical details) (A cool video) (Go Bears)

Volumetrically photopolymerized structures as opposed to traditional layer-by-layer deposition methods⁵.

References

¹Au, A. K., Huynh, W., Horowitz, L. F. & Folch, A. 3D-Printed Microfluidics. Angew. Chemie - Int. Ed. 55, 3862–3881 (2016). DOI: 10.1002/anie.201504382

²Ngo, T. D., Kashani, A., Imbalzano, G., Nguyen, K. T. Q. & Hui, D. Additive manufacturing (3D printing): A review of materials, methods, applications and challenges. Compos. Part B Eng. 143, 172–196 (2018). DOI: 10.1016/j.compositesb.2018.02.012

³Gong, H., Bickham, B. P., Woolley, A. T. & Nordin, G. P. Custom 3D printer and resin for 18 μm × 20 μm microfluidic flow channels. Lab Chip 17, 2899–2909 (2017). DOI: 10.1039/C7LC00644F

⁴Bose, S., Ke, D., Sahasrabudhe, H. & Bandyopadhyay, A. Additive manufacturing of biomaterials. Prog. Mater. Sci. 93, 45–111 (2018). DOI: 10.1016/j.pmatsci.2017.08.003

⁵Kelly, B. E. et al. Volumetric additive maufacturing via tomographic reconstruction. Science (80-. ). 126, 21 (2019). DOI: 10.1126/science.aau7114

References

Au, Anthony K, Wilson Huynh, Lisa F. Horowitz, and Albert Folch. "3d-printed Microfluidics." Angewandte Chemie International Edition. 55.12 (2016): 3862-3881. Print

Hausman, Kalani K, and Richard Horne. 3d Printing for Dummies. , 2014. Internet resource.

Kang, HW, SJ Lee, IK Ko, C Kengla, JJ Yoo, and A Atala. "A 3d Bioprinting System to Produce Human-Scale Tissue Constructs with Structural Integrity." Nature Biotechnology. 34.3 (2016): 312-9. Print.

Lee Lerner, K. "3D Printing." The Gale Encyclopedia of Science, edited by K. Lee Lerner and Brenda Wilmoth Lerner, 5th ed., vol. 8, Gale, 2014, p. 4383. Gale Virtual Reference Library, silk.library.umass.edu/login?url=http://go.galegroup.com/ps/i.do?p=GVRL&sw=w&u=mlin_w_umassamh&v=2.1&it=r&id=GALE%7CCX3727802429&asid=0eb5397745510438593a6c6b6c9698a1. Accessed 16 Feb. 2017.

Murphy, Sean V., and Anthony Atala. "3D Bioprinting of Tissues and Organs." Nature Biotechnology 32.8 (2014): 773-85. Web.