A travelling wave dielectrophoretic pump for blood delivery.

The travelling wave dielectrophoretic pump studied here is essentially a rectangular straight micro-channel with an electrode array on part of its wall, and operated under an ac voltage with phase shift at neighbouring electrodes. The travelling wave dielectrophoretic force drives the cells, which drag the plasma, and after some sophisticated interaction between conventional dielectrophoresis, travelling wave dielectrophoresis and fluid mechanics, the whole blood is delivered. The pump was fabricated using MEMS techniques and studied in details for different parameters. It is found that the pumping velocity is maximized at an intermediate frequency around 20-30 MHz (varies with phase shift), and at an intermediate channel height at about 40 microm. The quasi-static average cell velocity can reach 15 microm s(-1) for a pump with 1 mm length and 16 electrodes (total array length 465 microm) operated at 5 V and 20 MHz with 90 degrees phase shift.