Pillar of Engineering Product Development, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore.
School of Mechanical Engineering, Guangxi University, Nanning 530004, China.
ACS Sens. 2024 Oct 25;9(10):5275-5283. doi: 10.1021/acssensors.4c01467. Epub 2024 Sep 25.
Droplet microfluidic systems have emerged as indispensable and advanced tools in contemporary biological science. A prominent example is the droplet digital polymerase chain reaction (ddPCR), which plays a pivotal role in next-generation sequencing and the detection of rare nucleic acids or mutations. However, existing optical detection configurations are bulky, intricate, and costly, and require meticulous optical alignment to optimize fluorescence sensing. Herein, we propose a lab-in-fiber optofluidic system (LiFO), which provides a stable and compact footprint, self-alignment, and enhanced optical coupling for high-accuracy ddPCR. Moreover, LiFO could expand its capabilities for multiangle-scattering light collection in which we collect focused forward-scattering light (fFSL) to enable real-time droplet counting and size monitoring. To accomplish these attributes, LiFO incorporates optical fibers, along with fabricated PDMS grooves, for a self-aligned optical setup to implement simultaneous fluorescence and scattering detection. Furthermore, LiFO harnesses the concept of flowing droplets functioning as microlenses, which allows us to collect and translate fFSL signals into droplet size information. We have demonstrated the effectiveness of LiFO in ddPCR applications, illustrating its capacity to enhance the accuracy and precision of DNA quantification. Notably, LiFO exhibits improved linearity in the measurement of serial DNA dilutions, reflected by an increase in from 0.956 to 0.997. These results demonstrate the potential of LiFO to serve as a valuable tool across a wide spectrum of droplet microfluidic platforms, offering opportunities for advancement in practical applications.
液滴微流控系统已成为当代生物科学中不可或缺的先进工具。一个突出的例子是液滴数字聚合酶链反应（ddPCR），它在下一代测序和稀有核酸或突变体的检测中起着关键作用。然而，现有的光学检测配置体积庞大、复杂且昂贵，并且需要进行精密的光学对准以优化荧光传感。在此，我们提出了一种光纤内的实验室光学流体系统（LiFO），它提供了稳定紧凑的基础、自对准和增强的光学耦合，用于高精度的 ddPCR。此外，LiFO 可以扩展其能力，实现多角度散射光收集，我们收集聚焦前向散射光（fFSL），以实现实时液滴计数和大小监测。为了实现这些特性，LiFO 结合了光纤和制造的 PDMS 槽，实现了自对准的光学设置，以实现荧光和散射的同时检测。此外，LiFO 利用了作为微透镜的流动液滴的概念，使我们能够收集和转换 fFSL 信号以获取液滴大小信息。我们已经证明了 LiFO 在 ddPCR 应用中的有效性，表明它能够提高 DNA 定量的准确性和精度。值得注意的是，LiFO 在测量连续 DNA 稀释时的线性度得到了改善， 从 0.956 增加到 0.997。这些结果表明，LiFO 有潜力成为各种液滴微流控平台的有价值工具，为实际应用的发展提供了机会。
