Highly efficient and controllable micromixer through interactions of photothermal multivortices

The efficient and homogeneous mixing of fluids is crucial for microfluidic applications, such as chemical reactions, biological analyses, and material synthesis. This study designs a novel micromixer for efficient and controllable mixing based on photothermal vortices, which are generated from an array of linear heat sources as excited by a laser. The mixing performance is theoretically investigated using a multiphysics-coupled system based on the finite element method. We reveal the interactions between vortices and the mixing mechanism of fluids. The vortices provide a stable strength and adjustment ability to disturb fluid interfaces and enhance the mixing efficiency. Additionally, the effects of the vertical distance between two waveguides, optical power, and inlet mean velocity on the mixing performance are explored. As a result, the calculated mixing efficiency is 99.89%, which could be regarded as an important reference of the micromixer with an excellent mixing performance. The purpose of this study is to provide a new method for rapid, efficient, and controllable mixing for a myriad of chemical research and biotechnological applications.