Patent ID: 8734131

Claim:
A fluid pump comprising: a chamber which, in use, contains a fluid to be pumped, the chamber including a main cavity having a substantially cylindrical shape bounded by first and second end walls and a side wall and a secondary cavity extending radially outwards of the main cavity; one or more actuators which, in use, cause oscillatory motion of the first end wall in a direction substantially perpendicular to the plane of the first end wall, the actuator including an active element which is either a piezoelectric ring or a magnetostrictive ring, the active element being excited in a radial mode to induce axial deflection of one or both of the end walls, the distance between the inner and outer circumferences of the ring being approximately one quarter of a wavelength of the actuator mode-shape; and whereby, in use, the axial oscillations of the first end wall drives radial oscillations of the fluid pressure in the main cavity; and wherein the secondary cavity spaces the side wall from the first end wall such that the first end wall can move relative to the side wall when the actuator is activated.