The VAMP - A new device for handling liquids or gases

We present a new device, the VAMP, which is both an active microvalve and a forward- and reverse-working micropump (VAMP = Valve And MicroPump). Driven by a d.c. voltage, the VAMP operates in its valve mode and is able to control fluid flow in both directions. Driven by a square wave or a sinusoidal voltage, the VAMP operates in its pump mode and is able to pump fluids in both directions. The direction of fluid transport can be changed by varying the driving frequency of the actuator. We discuss two new mechanisms, which in combination are responsible for this frequency-dependent pump effect. The VAMP has been successfully tested for liquids (water, oil) and air. Using water we have achieved maximum pump rates of more than 2000 mu l min(-1) in the forward direction and 1200 mu l min(-1) in the reverse direction. The maximum back pressure is 17 kPa (1.7 mH(2)O) at a supply voltage of 200 V. Pumping air, we have achieved a maximum flow rate of 8000 mu l min(-1) in both directions. The VAMP has been manufactured in a small-lot production and is now available for industrial evaluation.