MacDonald M P, Spalding G C, Dholakia K
School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK.
Nature. 2003 Nov 27;426(6965):421-4. doi: 10.1038/nature02144.
The response of a microscopic dielectric object to an applied light field can profoundly affect its kinetic motion. A classic example of this is an optical trap, which can hold a particle in a tightly focused light beam. Optical fields can also be used to arrange, guide or deflect particles in appropriate light-field geometries. Here we demonstrate an optical sorter for microscopic particles that exploits the interaction of particles-biological or otherwise-with an extended, interlinked, dynamically reconfigurable, three-dimensional optical lattice. The strength of this interaction with the lattice sites depends on the optical polarizability of the particles, giving tunable selection criteria. We demonstrate both sorting by size (of protein microcapsule drug delivery agents) and sorting by refractive index (of other colloidal particle streams). The sorting efficiency of this method approaches 100%, with values of 96% or more observed even for concentrated solutions with throughputs exceeding those reported for fluorescence-activated cell sorting. This powerful, non-invasive technique is suited to sorting and fractionation within integrated ('lab-on-a-chip') microfluidic systems, and can be applied in colloidal, molecular and biological research.
微观介电物体对施加的光场的响应会深刻影响其动力学运动。一个典型的例子就是光阱，它可以将粒子捕获在紧聚焦的光束中。光场还可用于在适当的光场几何结构中排列、引导或使粒子偏转。在此，我们展示了一种用于微观粒子的光学分选器，它利用粒子（生物或其他粒子）与扩展的、相互连接的、动态可重构的三维光学晶格之间的相互作用。这种与晶格位点的相互作用强度取决于粒子的光学极化率，从而提供了可调谐的选择标准。我们展示了按尺寸（蛋白质微胶囊药物递送剂的尺寸）分选和按折射率（其他胶体粒子流的折射率）分选。该方法的分选效率接近100%，即使对于浓度较高的溶液，其吞吐量超过荧光激活细胞分选所报道的值，也能观察到96%或更高的分选效率。这种强大的非侵入性技术适用于集成（“芯片实验室”）微流体系统内的分选和分级分离，可应用于胶体、分子和生物学研究。
