US Patent 7128403 Microactuator and fluid transfer apparatus using the same

A microactuator using a shape memory alloy includes a substrate in which a space portion is formed, and a vibration plate which is installed on an upper surface of the substrate to cover the space portion, including a thin film formed of the shape memory alloy and at least one thin film on which a compressive residual stress acts. The vibration plate is initially transformed to bend to the space portion or to bend to be opposite to the space portion due to a bending moment caused by a compressive residual stress with respect to a first neutral axis, when the shape memory alloy is phase-transformed due to temperature rise.