Estudio de la evolución de flujos termocapilares inducidos con un laser IR en películas delgadas de agua para la manipulación de micro-objetos

Abstract

Nowadays, micromanipulation has an important role for assembly of micro-electromechanical components, because it enables to assemble very small components with different material properties and geometrical shapes in order to create complex multifunctional systems. Also, micromanipulation has contributed significantly in the field of medicine enabling manipulation of cells, molecules and bio-particles to study their behavior. Thus, a micromanipulation method that could move biological objects and microcomponents in an accurate, fast and multiple manner is needed. The preferred methods in the microscale are non-contact methods because they allow manipulating objects without damage or contamination. In this scope, microflows are very good candidates to drag micro-objects according to the flows direction and velocity, producing a drag force over the objects. In this research work, a study, through multiphysics simulations, on the thermocapillary flows generation within thin liquid layers is presented as a non-contact manipulation method. The high flows dynamics can move objects at high speed. This method consists of imaparting a very small temperature gradient at the liquid-air interface of a thin liquid layer, thus generating toroidal-shaped flows centered at the hot spot. So the objects inside the flows are dragged. This study allowed us to understand the temporal evolution of flows and how they could be generated in a controlled manner. Besides, it exists a radial distance with respect to the hot spot where is most suitable to place the objects to manipulate them at high speed due to the velocity profile. Flows speeds in the order of  were obtained using an infrared laser of about 80 mW. Simulations results showed that it is possible to establish a liquid depth in order to manipulate objects with specific sizes. As a result, manipulation strategies are being carried out to accurately move objects at high speeds.