MEMS Acoustic Cooling for Thin Computing Devices
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Solution Overview
Problem
Existing cooling solutions for computing devices, including both active and passive systems, struggle to effectively manage heat in both mobile and larger devices, leading to performance throttling and noise issues.
Innovation Solution
The implementation of an active MEMS cooling system that incorporates a heat transfer structure with a heat spreader, a fin structure, and a differential pressure device. This system generates a low-pressure region to draw fluid through the fin structure, effectively transferring heat from the heat spreader to the fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If active cooling devices such as fans are used to drive air through computing devices, then heat removal capability is improved, but device size and complexity increase
Solution Approach 1:
The patent replaces traditional mechanical fans with a MEMS-based acoustic wave generator that uses piezoelectric actuators to create standing acoustic waves. This substitutes mechanical rotation with acoustic field-based fluid pumping, reducing mechanical complexity while maintaining heat removal capability. The acoustic waves directly drive fluid flow through the heat exchanger without requiring rotating components.
Solution Approach 2:
The invention integrates the cooling system into the device thickness dimension by using thin-film MEMS structures and acoustic standing waves that operate within confined spaces. The acoustic field enables three-dimensional fluid circulation within a planar footprint, allowing effective heat removal without increasing the device's lateral dimensions.
2Productivity
If passive cooling devices such as heat spreaders are used in mobile devices, then device portability is improved, but heat removal capability is insufficient
Solution Approach 1:
The patent employs acoustic waves to create pneumatic pumping action that actively circulates fluid through the heat exchanger. The standing acoustic waves generate acoustic radiation pressure and acoustic streaming effects that drive fluid flow, enabling active heat removal in a passive device configuration without mechanical pumps or fans.
Solution Approach 2:
The system changes the operational parameters by using resonant acoustic frequencies to maximize fluid flow efficiency. By tuning the acoustic wave frequency to match the resonant frequency of the fluid cavity, the system achieves enhanced fluid circulation and heat transfer with minimal energy input, overcoming the limitations of passive cooling.
3Temperature
If traditional active cooling systems are incorporated into thin computing devices, then heat management is improved, but noise levels increase
Solution Approach 1:
The patent eliminates mechanical fans and their associated noise by replacing them with an acoustic field-based system. The piezoelectric actuators generate ultrasonic frequency acoustic waves that are inaudible to humans, creating fluid flow without the audible noise generated by mechanical fan blades cutting through air.
Solution Approach 2:
The system uses periodic acoustic wave generation at ultrasonic frequencies to drive fluid flow. The high-frequency periodic oscillation of the piezoelectric actuators creates continuous acoustic streaming that maintains fluid circulation without the intermittent noise characteristic of mechanical fan operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution achieves efficient heat transfer, with the ability to eject greater than 2 W of heat, and operates within a compact form factor suitable for thin computing devices, improving performance and reducing noise.
Implementation Method 1
the acoustic radiation pressure generated by the piezoelectric actuator is sufficient to overcome the backpressure of the fluid flow through the heat transfer structure
Implementation Method 2
a heat transfer structure with a heat spreader, a fin structure
Implementation Method 3
draws the fluid from an ingress in the computing device through the heat transfer structure
Data Source
AI summary
A cooling system for a computing device is described. The cooling system includes a heat transfer structure. The heat transfer structure includes a heat spreader, a fin structure, and a differential pressure device. The fin structure transfers heat from the heat spreader to a fluid. The differential pressure device generates a low pressure region that draws the fluid from an ingress in the computing device through the fin structure. The heat transfer structure is enclosed in a chamber of the computing device. The chamber includes the ingress and an egress.