Relationship between contact angle of liquid droplet and light beam position in optoelectrowetting

The contact angle of a liquid droplet on a dielectric-coated electrode can be controlled by changing the voltage between them. In addition, the insertion of a photoconductor between the dielectric layer and the electrode enables the optical control of the contact angle. In particular, by using a convergent light beam such as a laser beam, the voltage applied between the liquid droplet and the electrode can be changed locally; the contact angle can be controlled by changing the position of the convergent light beam. In this paper, we theoretically analyze the relationship between the contact angle and the position of a Gaussian light beam.