Numerical description of the manipulation of non-sphericalparticles by optical tweezers- A combined optical and hydrodynamic approach -

光学镊子(OT)在生物学和医学中被用作一种公认的工具。这项技术允许对微型物体和单个细胞进行无接触操作。由于OTS可以彼此穿透而不受影响，因此可以同时处理多个对象。由于这个原因，OTS在微技术中变得更加普遍，例如，用于组装复杂结构的物体或作为微型电机或泵的驱动力。为了增强该方法对该领域的可用性，有必要对底层流程有更深入的了解。遗憾的是，大多数关于激光与被操纵物体之间相互作用的理论研究仅限于球形或椭圆形。为了克服这些局限性，我们计划将基于几何光学的力计算模型推广到任意形状的物体。下一步也是最重要的一步将是动态行为的模拟。大多数光镊子用于液体环境中，因为与空气相比的高阻尼性确保了对颗粒的稳定捕获。因此，还必须考虑水动力。在这个项目中，我们将提供一种方法，通过几何光学和流体力学的结合，更完整地描述光镊子中的动态过程。数值分析的结果也将得到实验验证。

Optical tweezers (OTs) are used as an established tool in biology and medicine. This technique allows the contact-free manipulation of micro-sized objects and single cells. Since OTs can penetrate each other without influence, multiple objects can be handled simultaneously. For this reasons, OTs have become more prevalent in micro technolgy, e.g. for the assembling of complex structured objects or as a driving force for micro-scaled motors or pumps. To enhance the usability of the method to this field, a deeper understanding of the underlying processes is necessary. Unfortunately, most theoretical studies of the interaction between the laser light and the manipulated objects are restricted to spherical or elliptical shapes. Besides, only the static case is considered.To overcome the limitations, we plan to extend in a first step the geometrical optics based model for the force calculation to arbitrary shaped objects. The next and most important step will be the simulation of the dynamical behavior. Most optical tweezers are used in a liquid environment, since the high damping, e.g. in comparison to air, ensures a stable trapping of the particle. For this reason, the hydrodynamic forces must also be taken into account. Within this project, we will provide a method for a more complete description of dynamical processes in optical tweezers with the help of a combination of geometrical optics with hydrodynamics. The results of the numerical analysis will be also verified experimentally, as well.