(323h) Induced Recycle Flow in a Microchannel Using Electroosmosis

Krishnaveni, T., Indian Inistitute of Technology (IIT),Madras
Renganathan, T., Indian Institute of Technology Madras
Pushpavanam, S., Indian Institute of Technology, Madras
Lab on chip devices involves flow through the channel whose characteristic dimension is less than a millimetre. Recycle flows can be used to increase the residence time of a fluid and improve the mixing efficiency etc. In this work, we propose a novel method to recycle the fluid in microfluidic devices through a combination of electroosmosis and pressure driven flow in an electrolyte solution. The system consists of flow through a main channel and a side channel which is parallel to the main channel. The flow through entire microchannel is pressure driven and an electric field is applied across the side channel to reverse the fluid flow. When the applied electric field is sufficiently large i.e. greater than a critical value, the flow in the side channel is reversed and recycle is induced. The critical value of applied electric field beyond which recycle is induced is investigated as a function of zeta potential. The dependence of pressure and flowrates in the main and channels on applied electric is studied. The effect of geometric parameters such as radius and position of the side channel is analysed on flow behaviour in this work. The simple model proposed here provides valuable insight into the functioning of the device.