Fluid ejection device

A fluid ejection device, a method and an operation method thereof are disclosed. The fluid ejection device includes a substrate, a beam and an activation pad. The substrate has an orifice, and the beam includes a fixed portion and a cantilever portion and is disposed over the substrate, wherein the cantilever portion is disposed over the orifice. Furthermore, the activation pad is disposed between the cantilever portion of the beam and the substrate. Because the fluid ejection device of the present invention is fabricated by using micro-electromechanical technology, and therefore it possible to obtain a fluid ejection device capable of ejecting the fluid from the orifice at a high-speed and also the quantity fluid ejected can be very small.