The Core Engine of Miniature Liquid Cooling: Inside the Piezo Micro Pump

1.Challenge at the Heart of Miniature Liquid Cooling
2.How a Piezo Micro Pump Actually Works
3.The Advantage of Using the Piezo Micro Pump in Liquid Cooling
4.BESTAR: High Performance Miniature Liquid Cooling Solutions
5.Looking Forward: Small Pumps Big Impact

Challenge at the Heart of Miniature Liquid Cooling
Consider the devices the people use everyday. Facing headsets that stay on your face for hours of gaming. Wearing face-mounted VR headsets for hours of play. A thin as a pencil smartwatch. Laptops that weigh less than 1 kg, but have a powerful processor. The problem with all of these devices is they create a lot of heat and in such a small area.
Then, heat is not a sign of discomfort. This is the reason for devices slowing down, crashing or dying early. Processors have a built-in internal cooling system that slows down the processor when it becomes hot to prevent it from being damaged. It is maddening to users.
The most basic solution is air cooling. Apply air on hot surface, heat is carried along by the air stream. However, air is not a very good conductor of heat. Then in a device as small as a wristwatch and/or VR glasses, there's little space for fans or for ventilation to flow through. At this scale, air cooling is very limited.
The basic principle is that liquid cooling is more efficient. Water and other fluid coolants have great heat absorption capabilities compared to air. The point is pump.
The conventional method of pumping relies upon rotating motors, bearing and sealing mechanisms. They're dependable in large scale but challenging to scale down, as they might not retain performance or they might produce noise and vibration. For years it was a deep challenge finding a pump small enough to fit into a cell phone or a pair of AR glasses and yet had enough pumping action to sufficiently cool the processor. The piezo micro pump is the answer to this problem. It is the element that leads to Liquid Cooling at the scale which the actual miniature devices require.

How a Piezo Micro Pump Actually Works
It's easy to understand how a piezo micro pump works even if you don't have a degree in engineering. The fundamental concept is simple:
1. Use piezoelectric effect: Some ceramics are peculiar with regard to a specific property. They change shape if an electric voltage is turned on them. The deformation is very small. The question before us relates to some microns of displacement. But it is exact, rapid, repeatable millions of times and without wear-out of the material. This is known as the inverse piezoelectric effect and it is on this that the pump works.
2. The membrane moves. A thin disk of Piezo Ceramic is attached to a flexible membrane in a Piezo Micro Pump. A voltage causes the ceramic to deform. The membrane flexes. If the voltage is turned off or goes the other way, the membrane goes back to its starting position. The pump's motive is a back-and-forth action.
3. The chamber breathes. The layer of membrane is overlaid with a small fluid chamber. The chamber volume is increased when the membrane is flexed upwards. So this forms an area of reduced pressure within the chamber. Fluid is drawn in through the inlet. As the membrane flexes back down, the volume of the chamber can be seen to be less. Pressure increases. Pressing through the opening, fluid is driven out. This is the same concept as squeezing and releasing a bulb syringe except that on this occasion it is electronic, high frequency and on the scale of the fingertip.
The liquid is flowing in a single direction. An important question would be: does the membrane pull fluid in the opposite direction during the reversal? No, due to the valve structure. The majority of piezo micro pumps include passive check valves at the inlet and outlet. They are small flaps or disc structures which enable fluid to flow one way without any back flow. Consequently, although the membrane is reciprocating vibration, the fluid only flows along one continuous direction through the pump.
The more advanced designs are without valves. These depend on the geometry of the fluid channels themselves to cause a flow bias in one direction. This is possible using the physics of fluid dynamics on the micro scale and it gets rid of another mechanical part of the system, further enhancing reliability.
This cycle is repeated thousands of times per second. The piezoelectric ceramic impacts with very high frequencies (many thousands times per second) as it is affected by electrical signals, allowing the pump to cycle many thousands of times a second. What appears as a pulsating mechanism at the slow operating speed turns on the system level into a continuous and smooth flow. Like on a large regular pump, the fluid operates the pump steadily and continuously.

The Advantage of Using the Piezo Micro Pump in Liquid Cooling
While only the working principle matters, the practical advantages offered in the actual design of the application device make the piezo micro pump truly useful for product engineers.
The first advantage is the size. The piezo micro pump is a "no motor, no shaft, no impeller and no bearing assembly" pump. The whole pumping mechanism is made up of a ceramic disc and two small check valves. This enables pumps to be produced in a format not possible with traditional rotary pump technology. The BESTAR MMP10 Miniature Metal Liquid Pump, for instance, can be accommodated in the internal layout of consumer electronics. That is not an incremental improvement; that is quite an improvement. 
The low noise is the next benefit. Motors with rotations create mechanical noise. Bearings vibrate. Impellers create turbulence. Any sound or vibration in a consumer device which is audible or felt on the wrists or face will be instantly apparent and degrades impressions of quality. A piezo micro pump operates at a frequency at which near-zero acoustic output is achieved. It is invisible and inaudible to the user. It isn't there for them to feel. 
The fourth advantage is the response time. With the piezoelectric ceramic technology, the change in the voltage is passed to microseconds. The pump can deliver flow from no flow to full flow practically instantaneously. In an application where the processor suddenly and unexpectedly demands a lot more cooling power, this responsiveness translates into the ability of the cooling system to keep the chip within its thermal limits during peak loads.
The electromagnetic cleanliness is the fifth advantage. Electromagnetic interference is the result of rotating motors. That's interference that can create a problem in devices that rely on sensitive sensors, radio antennas or precise measurements. A piezo pump is a pump that is powered by deformation of piezoelectric ceramics when a voltage is applied. It produces a non-rotating magnetic field and also little electromagnetic noise. It does not need extra “shielding” or any other modifications to the circuit layout and can be used in modern electronic devices without harming the sensitive electronics.

BESTAR: High Performance Miniature Liquid Cooling Solutions
MMP07/MMP10 miniature metal liquid pump is tailored for small liquid coolers for hardware with space limitations. The pump provides enhanced thermal and mechanical strength. The operational sound is low enough that would not be heard in usual applications. The flow rate is adequate to provide meaningful heat transfer from contemporary high performance processors, as with a proper designed form of cold plate and heat exchanger.
BESTAR supplies you not only with the pump itself but also a complete cooling solution. The engineering team collaborates with the product developer to design the entire fluid path (how the fluid will flow around the system) with the cold plate geometry that is in contact with the processor, the micro channel configuration that maximizes heat transfer, as well as the heat rejection element that finishes the circuit. This support is available to help design and implement a product from the conception phase to its prototype and eventual mass production to meet functional requirements. The ability to have a supplier who not only supplies the component but can also support a thermal solution rather than just providing a solution in the form of a component can be significant for a product team which has not only a specific timeline for the thermal solution but also a specific device envelope.

Looking Forward: Small Pumps Big Impact
Liquid cooling technolpgy is used to come from top of the line desktop computers and industrial equipment. The limiting factor was the pump. It was too large, too loud, too energy-intensive and too unpredictable to fit in any size, be carried around and be worn on the body. The piezo micro pump turns that equation on its head. It ventures into the liquid-cooling world in the air-cooling or passive thermal-spreading realm.
These devices will be much more powerful versions of AR and VR headsets, thinner laptops featuring workstation-class processors, and next-generation wearables that include health monitoring sensors and consequently must be powered on at all times without the ability to manage the environment in which they are used, and they will all confront the same thermal problem. Less space, more heat and users who demand maximum performance of the device without the heat or noise.
Piezo Micro Pump is a well-featured, commercially viable and well-integrated portion of the thermal architecture that next generation devices will rely on. Sometimes processors on a device are not the limiting factor, but rather, how well the designers managed the heat issue. The piezo micro pump is one of the most useful aids to that problem that can be used in the smallest space. 
Welcome to contact BESTAR to know more about Miniature Liquid Cooling