Microrobots and micromachines based on optoelectronic tweezers

Optoelectronic tweezers (OET) are a state-of-art technique that combines light stimuli with electric field together by leveraging the photoconductive effect of semiconductor materials. Herein, the behavior of microobjects can be directly controlled by inducing the change of electric fields on demand in an optical manner. Relying on this light-induced electrokinetic effect, OET offer tremendous advantages in micromanipulation such as programmability, flexibility, versatility, high-throughput, and ease of integration with other characterization systems, thus showing impressive performance compared to those of many other manipulation techniques. A lot of research on OET has been reported in recent years and the technology has developed rapidly in various fields of science and engineering. In this chapter, we first introduce the working mechanism and typical structures of OET devices. Then, applications of OET in cell manipulation, cell analysis and cell electroporation are discussed. In the following part, OET-actuated microrobots and micromachines are introduced, including their working principles and applications. Finally, we overview the recent progress in the commercialization of OET technology for biopharmaceutical applications and end the chapter with challenges and future perspectives.