How do high-precision point control metering valves achieve precise control of liquid materials at the microliter or even nanoliter level?
Publish Time: 2025-08-25
In modern precision manufacturing, from semiconductor packaging and biochip spotting to bonding and coating microelectronic components, the dispensing accuracy requirements for liquid materials have reached the microliter or even nanoliter range. High-precision point control metering valves are core actuators designed to meet this extreme demand. Through advanced drive technology, precise fluid control mechanisms, and closed-loop feedback systems, they achieve stable, repeatable, and controllable delivery of extremely small amounts of liquid, becoming an indispensable "micromanipulator" in automated dispensing processes.Achieving precise control at the microliter or even nanoliter level depends primarily on the metering valve's actuation method. Traditional time-pressure valves rely on air pressure, and their accuracy is significantly affected by air source stability, temperature fluctuations, and fluid viscosity fluctuations, making them difficult to meet high-precision requirements. High-precision point control metering valves, on the other hand, commonly utilize advanced technologies such as piezoelectric drive, screw propulsion, or servo pneumatics. Piezoelectric drive technology is particularly prominent. Its principle is to use the micrometer-level deformation of piezoelectric materials under the action of voltage to directly drive the valve needle or piston for ultra-fine movement. This drive method offers extremely fast response speeds, enabling microsecond-level start and stop, and nanometer-level displacement control accuracy, ensuring precise and precise control of discharge volume.High-precision metering valves eschew crude pneumatic delivery in favor of a volumetric metering principle. For example, a screw-type metering valve uses a high-precision stepper motor to drive a microscrew, pushing the glue from the reservoir at a set angle. The discharge volume is precisely determined by the screw's pitch, speed, and number of revolutions. Because the screw's movement is digitally controlled, the discharge volume remains constant with each revolution, enabling highly repeatable micro-dispensing. For high-viscosity fluids, the system can also dynamically adjust torque and speed to ensure stable flow and avoid pulsation or flow interruption.To accommodate the physical properties of diverse fluids, the flow path design of the metering valve is meticulously designed. The internal flow path features a smooth, seamless structure to reduce residual and shear stresses, preventing glue from clogging or solidifying within the microchannels. The valve orifice diameter can be adjusted to suit application requirements, ranging from tens to hundreds of microns. Combined with different spray patterns, precise shaping in a variety of shapes, such as dots, lines, arcs, or sprays, can be achieved. Some high-end metering valves also feature a "jetting mode," which allows the valve needle to open and close at high speed, ejecting tiny droplets to the target location without contacting the workpiece. This makes it suitable for high-speed, non-contact dispensing, avoiding component damage caused by probe collisions.The introduction of a closed-loop control system further enhances the metering valve's ability to maintain precision. The system integrates pressure sensors, flow monitoring modules, or visual feedback devices to monitor discharge status in real time and compare it with setpoints. If deviations are detected, the controller immediately adjusts the drive parameters to compensate. For example, during long-term operation, glue viscosity may decrease due to temperature increases, resulting in increased discharge volume. The closed-loop system will automatically reduce the drive stroke or pressure to maintain a stable dosage. This self-regulating capability ensures repeatability within ±1% even under complex operating conditions.Additionally, anti-drip and back-sucking functions are key to ensuring micro-dosage control accuracy. At the end of discharging, the control system instructs the drive unit to slightly reverse, generating a brief negative pressure that draws back any remaining colloid from the nozzle, completely eliminating dripping. This action is precisely controlled by the program to prevent bubbles from being introduced due to excessive back-drawing, which could affect the consistency of the next dispensing.High-precision point control metering valves also support seamless integration with motion platforms, machine vision, and higher-level control systems. Through digital communication protocols, they enable multi-valve coordination, path optimization, and real-time process adjustments, making them widely applicable in automated production lines.In summary, the high-precision point control metering valve, through the synergy of piezoelectric or screw drive, volumetric metering, closed-loop feedback, and intelligent control, has successfully broken through the technical bottleneck of microfluidics control. It not only achieves precise dispensing at the microliter or even nanoliter level, but also offers high repeatability, stability, and adaptability. It provides reliable technical support for precision manufacturing and is driving the continuous evolution of industries such as electronics, medical, and new energy towards higher precision and efficiency.
