A membrane micropump electrostatically actuated across the working fluid

A novel electrostatically actuated valveless micropump is presented whereby an actuation voltage is applied across a working fluid, which takes advantage of the higher relative electrical permittivity of water and many other fluids with respect to air. The device is fabricated in silicon and the diaphragm is made of electroplated nickel, while the assembly is carried out using flip–chip bonding. A reduced-order model is used to describe the micropump's performance in terms of electrical properties of the fluid, the residual stress in the diaphragm, geometrical features and the actuation voltage. The tested prototype featured a ∼1 µl min⁻¹ flow rate at 50 V actuation voltage. The model predictions show the possibility of achieving flow rates >1 µl min⁻¹ with the actuation voltage <10 V for devices with 3 mm diaphragm size.