Fundamental study of EHD pump with needle-cylinder electrodes

Since the recent CPU and the hard disks produce a large amount of heat, a quiet cooling system for such a device is required. There have been some attempts to make the system with micro machined EHD pumps by using polar liquids. Our attempt is to use a non-polar liquid as a working fluid in EHD pumping. The experimental apparatus consists of an ion injector with needle electrodes and a collecting electrode. In order to measure the pressure difference, U-shape configuration is adopted in which silicone fluid of 50 cSt is filled. From the experimental data, many interesting results were obtained. There is no pressure creation with positive polarity, contrary to negative polarity. Although the number of needle electrodes is important, there seems to exist a suitable number. The dependency of voltage is likely to follow the square law. Since the important factor for EHD pumping is fluid flow pattern, the design of electrodes is extremely important.