Manipulation of polystyrene sphere through a photodiode-induced dielectrophoretic force

• Main Authors: Su, Chi-Shiang, 蘇其祥
• Other Authors: Lee, Ming-Chang
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/d3twmy

碩士 === 國立清華大學 === 光電工程研究所 === 105 === 　Biological lab on chip usually requires a tool to move biological samples on an integrated device. Therefore, there is lots of research works focused on manipulating minute objects in a microfluidic chip. Two types of mechanisms are widely applied; one is optically-induced dielectricphoresis (ODEP) and the other is traveling-wave dielectrophoresis (twDEP). TwDEP cannot do multi-object control, and ODEP usually requires two parallel plates. A single control plate has advantage in integration with a micro-fluidic platform. In this research work, we present a photodiode-induced dielectrophoretic force to control Polystyrene spheres in liquid. The device is made of interdigitated lateral P-N junctions on an intrinsic silicon substrate. When the device operates in reverse bias without illumination, the voltage drop across the insulation layer exhibits a strong electric field in the space. On the other hand, when the device operates in reverse bias under illumination, the voltage drop reduces because photocurrent would pass through a resistor, which makes the electric field become weak. And the difference of induced positive DEP can make the particles toward a stronger electric field. While the internal resistance of our device is not sufficient, we need to add an external resistor to achieve our goal. At the end, we propose a new design of device to increase the internal resistance.