DTU Nanotech-Department of Micro and Nanotechnology, Technical University of Denmark, Kgs. Lyngby, Denmark.
Electrophoresis. 2012 Jul;33(12):1715-22. doi: 10.1002/elps.201100674.
In this paper, we describe a microfluidic device composed of integrated microoptical elements and a two-layer microchannel structure for highly sensitive light scattering detection of micro/submicrometer-sized particles. In the two-layer microfluidic system, a sample flow stream is first constrained in the out-of-plane direction into a narrow sheet, and then focused in-plane into a small core region, obtaining on-chip three-dimensional (3D) hydrodynamic focusing. All the microoptical elements, including waveguides, microlens, and fiber-to-waveguide couplers, and the in-plane focusing channels are fabricated in one SU-8 layer by standard photolithography. The channels for out-of-plane focusing are made in a polydimethylsiloxane (PDMS) layer by a single cast using a SU-8 master. Numerical and experimental results indicate that the device can realize 3D hydrodynamic focusing reliably over a wide range of Reynolds numbers (0.5 < Re < 20). Polystyrene particles of three sizes (2, 1, and 0.5 μm) were measured in the microfluidic device with integrated optics, demonstrating the feasibility of this approach to detect particles in the low micrometer size range by light scattering detection.
在本文中，我们描述了一种由集成微光学元件和两层微通道结构组成的微流控装置，用于对微/亚微米尺寸的颗粒进行高灵敏度的光散射检测。在两层微流控系统中，首先将样品流限制在平面外方向，形成狭窄的薄片，然后在平面内聚焦成小的芯区，实现片上三维（3D）流体动力学聚焦。所有微光学元件，包括波导、微透镜和光纤-波导耦合器，以及平面内聚焦通道，均由标准光刻技术在一层 SU-8 中制造。用于平面外聚焦的通道由 PDMS 层通过 SU-8 母版的一次浇铸制成。数值和实验结果表明，该器件可以在较宽的雷诺数范围（0.5 < Re < 20）内可靠地实现 3D 流体动力学聚焦。在具有集成光学器件的微流控装置中测量了三种尺寸（2、1 和 0.5 μm）的聚苯乙烯颗粒，证明了通过光散射检测检测低微米尺寸范围内颗粒的这种方法的可行性。
