Modeling and Numerical Studies of Three‐Dimensional Conically Shaped Microwells Using Non‐Uniform Photolithography

Abstract

Conical microwells have found a wide range of applications such as in cancer diagnostics, cell spheroid formation, and three-dimensional oncology models. Numerous microengineered fabrication techniques have been developed for the formation of such conically shaped microwells. Among many, non-uniform photolithography (NUPL) in a PDMS microfluidic channel with a glass substrate, can be used to create polymeric microwells with tapered-bottom and parabolic curvatures. Here, the parabolic well formation of microwells is numerically investigated using NUPL to better understand its key mechanisms. Temporal and spatial free-radical diffusion are incorporated into the modeling of photopolymerization. In addition, the 3D-shape tuning ability of NUPL is modeled for the synthesis of microwells through a variation of UV light intensity induced by the presence of opaque materials. The model and simulation results predict the time-evolution of microwell formation with parabolic well features. The effects of the conical shape-tuning parameters are numerically determined, i.e., the aspect ratio of the well diameter to channel height and the non-uniformity of UV light intensity on the microwell depth and parabolic curvature. Numerical work provides meaningful insights into NUPL to optimize and design polymeric microwells with shape features tuned to their application.

One-step Non-uniform Photolithography System for Three-dimensional Conically Shaped Microwell Fabrication

“…, Appendix D) is shorter than that of the polymeric microwells (~ 50 µm, FigureD1b, Appendix D) because of the UV absorption caused by the magnetic nanoparticles, which significantly decreases the UV intensity, resulting in a UV light gradient along the transmission direction. The reactiondiffusion process model also predicts that V-shape microwells exhibit a thicker oxygen inhibition layer than polymeric microwells(Manzoor & Hwang, 2022).…”

One-step Non-uniform Photolithography System for Three-dimensional Conically Shaped Microwell Fabrication

“…, Appendix D) is shorter than that of the polymeric microwells (~ 50 µm, FigureD1b, Appendix D) because of the UV absorption caused by the magnetic nanoparticles, which significantly decreases the UV intensity, resulting in a UV light gradient along the transmission direction. The reactiondiffusion process model also predicts that V-shape microwells exhibit a thicker oxygen inhibition layer than polymeric microwells(Manzoor & Hwang, 2022).…”

Stimuli‐Responsive Optical Switching Patterns in Millimetric Hydrogel Frames: Nanomaterial‐Free Anti‐Counterfeiting Technology

“…This free-radical polymerization outside the UV projected zone forms a thin hydrogel film, shorter than the hydrogel frame thickness. [37] This hydrogel film outside the UV projected zone is seen in Figure 3c, where bull eyes and noses are intact. Without the thin hydrogel film developed by the free-radicals diffusion-initiated polymerization, the eyes and noses should be disintegrated from the hydrogel frame.…”