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. 2024 Sep 10;121(37):e2405382121.
doi: 10.1073/pnas.2405382121. Epub 2024 Sep 4.

High-resolution stereolithography: Negative spaces enabled by control of fluid mechanics

Ian A Coates  1 , William Pan  2 , Max A Saccone  1   3 , Gabriel Lipkowitz  2 , Dan Ilyin  2 , Madison M Driskill  1 , Maria T Dulay  3 , Curtis W Frank  1 , Eric S G Shaqfeh  1   2 , Joseph M DeSimone  1   3
Affiliations

High-resolution stereolithography: Negative spaces enabled by control of fluid mechanics

Ian A Coates et al. Proc Natl Acad Sci U S A. .

Abstract

Stereolithography enables the fabrication of three-dimensional (3D) freeform structures via light-induced polymerization. However, the accumulation of ultraviolet dose within resin trapped in negative spaces, such as microfluidic channels or voids, can result in the unintended closing, referred to as overcuring, of these negative spaces. We report the use of injection continuous liquid interface production to continuously displace resin at risk of overcuring in negative spaces created in previous layers with fresh resin to mitigate the loss of Z-axis resolution. We demonstrate the ability to resolve 50-μm microchannels, breaking the historical relationship between resin properties and negative space resolution. With this approach, we fabricated proof-of-concept 3D free-form microfluidic devices with improved design freedom over device material selection and resulting properties.

Keywords: 3D-printing; microfluidics; negative-space; stereolithography; vat-polymerization.

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Conflict of interest statement

Competing interests statement:J.M.D. declares that he has an equity stake in Carbon Inc., a venture-backed start-up company that owns U.S. Patent 9,216,546, U.S. Patent 9,360,757, and other related patents. I.A.C., G.L., and J.M.D. declare that they are currently listed as inventors on a pending patent application for methods involving negative space preservation using iCLIP. The CLIP and iCLIP patents and patent applications are being licensed to a new vaccine and drug delivery company called PinPrint, which J.M.D. is a founder of and in which he holds an equity stake. M.A.S. advises 3D Architech Inc., a company specializing in vat photopolymerization-based metal 3D printing. The authors declare that they have no other competing interests.

Figures

Fig. 1.
Fig. 1.
iCLIP enables fabrication of microscopic negative structures. (A) Schematic of CLIP process and the resulting overcuring effect. (B) Schematic of iCLIP process and the resulting resolved negative structures. (C) Relationship between UV light penetration depth and minimum channel height of iCLIP and other DLP systems (–22). (D) Resulting microsystems including microfluidic distributer, vascular perfusion beds, and a microfluidic-enabled microarray patch printed via high-resolution iCLIP, with channels filled with dye for contrast. (Scale bar, 5 mm.)
Fig. 2.
Fig. 2.
Comparing model and experimental overcuring effects between CLIP and iCLIP processes. (A) UV light accumulation in the CLIP process and the resulting modeled overcuring effect. (B) CLIP print result. (C) UV light accumulation in the iCLIP process and the resulting sinuous channel resolution. (D) iCLIP print result. (Scale bar, 1 mm.)
Fig. 3.
Fig. 3.
Mitigating overcuring in varying microfluidic channel geometries and sizes. (A) Resulting CLIP and iCLIP prints of varying channel pitches. (B) Resulting CLIP and iCLIP prints of varying channel diameters. (C) Evaluating resolution of varying channel pitch geometries using the CLIP and iCLIP systems. (D) Evaluating resolution of varying channel diameters using the CLIP and iCLIP systems. All scale bars 1 mm.
Fig. 4.
Fig. 4.
Exploring microchannel resolution in relation to fresh resin turnover. (A) Resolution of a resin with penetration depth of 237 μm as a function of turnover number. (B) Relationship between a resin’s penetration depth and the minimum required turnover rate.
Fig. 5.
Fig. 5.
Diverse microsystem fabrication capabilities enabled by iCLIP. (A) Microfluidic enabled microneedle patch. (B) Microneedle patch with interconnected microfluidic channels. (C) Microfluidic inductor back-filled with conductive gallium. (D) Microfluidic microneedle patch with 3D micromixer. (E) Vascular perfusion chamber. (F) Porous media separation columns with varying void fraction unit cells. All scale bars 1 mm.
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References

    1. Grigoryan B., et al. , Multivascular networks and functional intravascular topologies within biocompatible hydrogels. Science 364, 458–464 (2019). - PMC - PubMed
    1. Therriault D., White S. R., Lewis J. A., Chaotic mixing in three-dimensional microvascular networks fabricated by direct-write assembly. Nat. Mater. 2, 265–271 (2003). - PubMed
    1. Wu S.-Y., Yang C., Hsu W., Lin L., 3D-printed microelectronics for integrated circuitry and passive wireless sensors. Microsyst. Nanoeng. 1, 15013 (2015).
    1. Sun K., et al. , 3D printing of interdigitated Li-ion microbattery architectures. Adv. Mater. 25, 4539–4543 (2013). - PubMed
    1. Sanchez Noriega J. L., et al. , Spatially and optically tailored 3D printing for highly miniaturized and integrated microfluidics. Nat. Commun. 12, 5509 (2021). - PMC - PubMed

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