A MEMS (Micro-Electro-Mechanical System) microscale microvalve is a miniaturized valve designed to control the flow of fluids in microfluidic systems. These devices are typically fabricated using semiconductor manufacturing techniques, allowing for precise control and integration with other microscale components on a chip.
The operation of a MEMS microvalve involves utilizing various physical mechanisms, often combined with electrical actuation, to regulate fluid flow. Here's a general description of its operation:
Structure: A MEMS microvalve consists of a tiny chamber or channel through which the fluid flows. The valve is composed of a movable part (actuator) and a stationary part (valve seat). The movable part can be a diaphragm, a cantilever beam, or any other microstructure that can block or permit the fluid flow.
Actuation: The microvalve's actuation can be achieved through various means, including electrostatic, piezoelectric, thermal, or magnetic actuation.
Electrostatic: By applying an electrical voltage across two conductive plates (one attached to the movable part and the other to the substrate), an electrostatic force is generated, causing the movable part to deflect and open or close the valve.
Piezoelectric: Using piezoelectric materials that deform when an electric field is applied, the valve can be actuated to control the flow.
Thermal: Heating the fluid or the actuator can change the pressure inside the valve, leading to the opening or closing of the valve.
Magnetic: By applying a magnetic field to a magnetic actuator, it can be attracted or repelled to actuate the valve.
Fluid Control: When the microvalve is in its closed state, the movable part seals against the valve seat, preventing fluid flow. In the open state, the movable part moves away from the valve seat, allowing fluid to pass through the channel.
Control Signal: The actuation of the microvalve is controlled by applying appropriate electrical signals to the actuator. This control signal can be generated by an external control system, often connected to a microcontroller or a computer, based on the desired fluid flow conditions.
Integration: MEMS microvalves are designed to be integrated into microfluidic devices, where they work in conjunction with other microfluidic components such as pumps, mixers, and sensors. This integration allows for precise fluid manipulation and control within a microfluidic system.
The advantages of MEMS microvalves include their small size, fast response times, low power consumption, and compatibility with mass production techniques, enabling the development of advanced and compact microfluidic systems for various applications such as lab-on-a-chip devices, biomedical diagnostics, chemical analysis, and environmental monitoring.