Visualization study on the interactions between water droplet and elastic film

The interactions between water droplets and elastic films were examined by acquiring droplet and PDMS film images using a high-speed visualization technique. The contact angle with a water droplet and the deflection of a PDMS thin polymer film were measured from the images and compared with the values calculated from modified cantilever theory. The contact angle and deflection of the PDMS thin plate increased with increasing droplet volume. The static behavior of the elasto-capillarity effect was confirmed by theory and experiment. The dynamic behavior of an elastic film was also examined using the AC electro-wetting condition. The elastic polymer with a droplet was vibrating at double the frequency of the excited AC frequency. The amplitude of vibration increased with increasing AC voltage. These results can be used to design practical microactuators. Graphical Abstract .