|Definition:|| mechanical device that controls the flow of fluid in a microscopic channel
Note 1 to entry: Microvalves, which are composed of such components as actuators and diaphragms, made of silicon, etc., control the flow in microscopic channels (narrower than several micrometres). For example, a gas flow control valve is composed of a stacked piezoelectric actuator and a diaphragm. To control high-viscosity fluids such as blood, it is necessary to enlarge the channel and increase the stroke of the valve drive. A mechanism using a shape-memory alloy coil and a bias spring has been developed experimentally for this purpose, as well as a mechanism that alters the channel by an electrostatic, magnetic, or piezoelectric actuator.