Smith Kaylee A, Habibi Sanaz, de Beer Martin P, Pritchard Zachary D, Burns Mark A
Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
Biomicrofluidics. 2022 Aug 3;16(4):044106. doi: 10.1063/5.0094721. eCollection 2022 Jul.
Microfluidic devices are typically fabricated in an expensive, multistep process (e.g., photolithography, etching, and bonding). Additive manufacturing (AM) has emerged as a revolutionary technology for simple and inexpensive fabrication of monolithic structures-enabling microfluidic designs that are challenging, if not impossible, to make with existing fabrication techniques. Here, we introduce volumetric stereolithography (vSLA), an AM method in which polymerization is constrained to specific heights within a resin vat, allowing layer-by-layer fabrication without a moving platform. vSLA uses an existing dual-wavelength chemistry that polymerizes under blue light (λ = 458 nm) and inhibits polymerization under UV light (λ = 365 nm). We apply vSLA to fabricate microfluidic channels with different spatial and vertical geometries in less than 10 min. Channel heights ranged from 400 m to 1 mm and could be controlled with an optical dose, which is a function of blue and UV light intensities and exposure time. Oxygen in the resin was found to significantly increase the amount of dose required for curing (i.e., polymerization to a gelled state), and we recommend that an inert vSLA system is used for rapid and reproducible microfluidic fabrication. Furthermore, we recommend polymerizing far beyond the gel point to form more rigid structures that are less susceptible to damage during post-processing, which can be done by simultaneously increasing the blue and UV light absorbance of the resin with light intensities. We believe that vSLA can simplify the fabrication of complex multilevel microfluidic devices, extending microfluidic innovation and availability to a broader community.
微流控设备通常采用昂贵的多步骤工艺制造（例如光刻、蚀刻和键合）。增材制造（AM）已成为一种革命性技术，可用于简单且廉价地制造整体结构，实现了用现有制造技术难以（甚至不可能）制造的微流控设计。在此，我们介绍体素立体光刻（vSLA），这是一种增材制造方法，其中聚合反应被限制在树脂槽内的特定高度，无需移动平台即可逐层制造。vSLA使用现有的双波长化学方法，在蓝光（λ = 458 nm）下聚合，在紫外光（λ = 365 nm）下抑制聚合。我们应用vSLA在不到10分钟内制造出具有不同空间和垂直几何形状的微流控通道。通道高度范围从400μm到1mm，可通过光剂量控制，光剂量是蓝光和紫外光强度以及曝光时间的函数。发现树脂中的氧气会显著增加固化所需的剂量（即聚合到凝胶状态），我们建议使用惰性vSLA系统进行快速且可重复的微流控制造。此外，我们建议聚合远远超过凝胶点以形成更刚性的结构，使其在后处理过程中不易受损，这可以通过同时增加树脂对蓝光和紫外光的吸光度以及光强度来实现。我们相信vSLA可以简化复杂多级微流控设备的制造，将微流控创新和可用性扩展到更广泛的群体。
