Electro wetting of liquid marbles

• Main Author: Chan, Yu Fung.
• Other Authors: Nguyen Nam-Trung
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Mechanical engineering::Fluid mechanics
• Online Access: http://hdl.handle.net/10356/46043
• Institution: Nanyang Technological University

The focus of this project is to design an experimental platform to perform electrowetting on liquid marbles and to characterise any reaction that the liquid marble may experience. An experimental setup was to be designed and produced to be able to perform the electrowetting process on the liquid marble. Several design considerations had to be taken into account during the fabrication of the setup, namely stability, freedom of motion as well as safety. The design of the base plate and slide holder, went through numerous changes before its final design, the pedestal had to be isolated from the extension arm and its mount so as to achieve its freedom to move in 3 axes without affecting the pedestal and the slide. The extension arm also had to be rigid and non-conducting so as to prevent accidental shorting of the DC source as the voltage application is very high. The mount had to be securely fastened down to the base plate so as to maximize the stability of the whole setup. Experiments were carried out by forming liquid marbles using 3 different liquids, deionised water, an electrolyte (saline solution) and nanofluid. The liquid marbles were made with volumes ranging from 1 µl to 9 µl. The marbles were then placed on a conducting surface, in this case Indium-Tin Oxide coated glass slide, and an electrode was gently inserted into the liquid marble and a voltage was applied. The voltage application started from 50 volts and the voltage was raised in 10volt increments. The marble’s reactions were observed and recorded at each 10volt increment, until the marble experiences a breakdown. A trend was observed that as the volume of marble increases, the breakdown voltage of the marble also increased, with the different fluids exhibiting different breakdown voltages for the same given volume. The marble also experienced violent ejection of some its powder shell particles in some instances. Future works can involve AC voltage sources to test the effect of various frequencies on the electrowetting effect.