Visualization study on the behaviors of oscillating liquid bridge between two parallel plates with surface treatments

Abstract

For more than a decade, energy harvesting devices have been rapidly developed based on the electrical energy conversion techniques from kinetic energy using piezoelectric, electrostatic, and electromagnetic principles. However, the amount of power is insufficient for practical products. Recently, a new concept of energy generation, the reverse electrowetting technology has been invented. This method demonstrates that an oscillating water bridge between two parallel conducting plates can generate an AC electric power. The electrical double-layer capacitors formed on the two interfacial areas of a water bridge and plates are continuously charged and discharged when the shape of the bridge between two plates while the bottom plate is oscillating. For this research, we treat surfaces of each plate hydrophilic and hydrophobic, give variety to vibration frequency, amplitude and droplet size. Though the images of liquid bridge taken by a high-speed camera, the size of contact area is measured and flow field is observed by PIV, then we find a correlation with output voltage signal. This observation could contribute to more accurate prediction of the behaviors of oscillating droplets and development of micro-fluidic power generation devices.