An Electrokinetic Valve in a Microchannel System
Model ID: 10
This model presents an example of pressure driven flow and electrophoresis in a microchannel system. The modeled device is often used as an electrokinetic sample injector in biochips with well-defined sample volumes of dissociated acids and salts. The model presents a study of a pinched injection cross valve during the focusing, injection, and separation stages. Focusing is obtained through pressure driven flow of the sample and buffer solution, which confines the sample in the focusing channel. This is done through coupling the flow, to the electrokinetic flow application mode. When steady state has been obtained, the pressure driven flow is turned off and an electric field is applied along the channels. The electric field drives the dissociated sample ions that are found in the focusing zone at right angles to the focusing channel, through the injection channel. This is solved in the time-domain. A clean separation of the sample ions is important and different configurations of the electric field are tested in order to achieve this.
|The concentration distribution during the injection stages. The graph of the separation step shows that there is good detachment of the sample and that the lower left corner does not create any problems.|