Over the past decade, additive manufacturing—or “three-dimensional (3D) printing”—has attracted increasing attention in the Lab on a Chip community as a pathway to achieve sophisticated system architectures that are difficult or infeasible to fabricate via conventional means. One particularly promising 3D manufacturing technology is “direct laser writing (DLW)”, which leverages two-photon (or multi-photon) polymerization (2PP) phenomena to enable high geometric versatility, print speeds, and precision at length scales down to the 100 nm range. Although researchers have demonstrated the potential of using DLW for microfluidic applications ranging from organ on a chip and drug delivery to micro/nanoparticle processing and soft microrobotics, such scenarios present unique challenges for DLW. Specifically, microfluidic systems typically require macro-to-micro fluidic interfaces (e.g., inlet and outlet ports) to facilitate fluidic loading, control, and retrieval operations; however, DLW-based 3D printing relies on a micron-to-submicron-sized 2PP volume element (i.e., “voxel”) that is poorly suited for manufacturing these larger-scale fluidic interfaces. In this Tutorial Review, we highlight and discuss the four most prominent strategies that researchers have developed to circumvent this trade-off and realize macro-to-micro interfaces for DLW-enabled microfluidic components and systems. In addition, we consider the possibility that—with the advent of next-generation commercial DLW printers equipped with new dynamic voxel tuning, print field, and laser power capabilities—the overall utility of DLW strategies for Lab on a Chip fields may soon expand dramatically.

中文翻译：

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适用于微流体应用的直接激光写入 3D 打印策略

在过去的十年中，增材制造（或“三维 (3D) 打印”）作为实现通过传统方法难以或不可行的复杂系统架构的途径，在芯片实验室社区中引起了越来越多的关注。一项特别有前途的 3D 制造技术是“直接激光写入 (DLW)”，它利用双光子（或多光子）聚合 (2PP) 现象来实现高几何通用性、打印速度和长度尺寸缩小到 100 的精度。纳米范围。尽管研究人员已经证明了将 DLW 用于微流体应用的潜力，从芯片上的器官和药物输送到微/纳米颗粒处理和软微机器人，但此类场景对 DLW 提出了独特的挑战。具体而言，微流体系统通常需要宏观到微观流体接口（例如入口和出口）以促进流体加载、控制和检索操作；然而，基于 DLW 的 3D 打印依赖于微米至亚微米尺寸的 2PP 体积元件（即“体素”），该元件不太适合制造这些更大规模的流体界面。在本教程回顾中，我们重点介绍并讨论了研究人员为规避这种权衡并为支持 DLW 的微流体组件和系统实现宏观到微观接口而开发的四种最突出的策略。此外，我们认为，随着配备新的动态体素调整、打印场和激光功率功能的下一代商用 DLW 打印机的出现，DLW 策略在芯片实验室领域的整体效用可能很快会大幅扩展。 。