Kim Jisu, Shin Jung H
KAIST, Department of Physics, 373-1 Guseong-dong, Yuseong-Gu, Daejeon, South Korea.
KAIST, Graduate School of Nanoscience and Technology, 373-1 Guseong-dong, Yuseong-Gu, Daejeon, South Korea.
Sci Rep. 2016 Sep 22;6:33842. doi: 10.1038/srep33842.
We demonstrate stable, free-space optical trapping and manipulation in an integrated microfluidic chip using counter-propagating beams. An inverted ridge-type waveguide made of SU8 is cut across by an open trench. The design of the waveguide provides low propagation losses and small divergence of the trapping beam upon emergence from the facet, and the trench designed to be deeper and wider than the optical mode enables full utilization of the optical power with an automatic alignment for counter-propagating beams in a trap volume away from all surfaces. After integration with polydimethylsiloxane (PDMS) microfluidic channel for particle delivery, 0.65 μm and 1 μm diameter polystyrene beads were trapped in free space in the trench, and manipulated to an arbitrary position between the waveguides with a resolution of < 100 nm. Comparison with numerical simulations confirm stable trapping of sub-micron particles, with a 10 kT threshold power of less than 1 mW and a stiffness that can be 1 order of magnitude larger than that of comparable fiber-based trapping methods.
我们展示了在集成微流控芯片中使用反向传播光束实现稳定的自由空间光捕获和操纵。由SU8制成的倒置脊型波导被一个开放沟槽横穿。波导的设计提供了低传播损耗，并且捕获光束从刻面出射时发散小，而设计得比光学模式更深更宽的沟槽能够在远离所有表面的捕获体积中实现反向传播光束的自动对准，从而充分利用光功率。在与用于粒子输送的聚二甲基硅氧烷（PDMS）微流控通道集成后，直径为0.65μm和1μm的聚苯乙烯珠被捕获在沟槽中的自由空间中，并被操纵到波导之间的任意位置，分辨率小于100nm。与数值模拟的比较证实了亚微米粒子的稳定捕获，10kT的阈值功率小于1mW，刚度比类似的基于光纤的捕获方法大1个数量级。
