MEMS Cryocooler with Shared Regenerator for Infrared Camera Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cryogenic refrigeration systems are large, costly, mechanically noisy, and provide insufficient cooling power to reach cryogenic temperatures required for infrared cameras, especially when dealing with thermal loads typical of operating infrared cameras.
Innovation Solution
A microelectromechanical systems (MEMS) cryocooler design featuring a MEMS expander assembly with a substantially contiguous shared regenerator thermally decoupled from the compressor assembly via a gas transfer line, allowing for increased cooling power and lower operating temperatures by reducing heat leak and enhancing regenerator size and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional mechanical cryogenic coolers are used, then cooling capability is provided, but the systems are large, costly to manufacture and maintain, and mechanically noisy
Solution Approach 1:
The patent replaces conventional mechanical cryogenic cooler components with microelectromechanical systems (MEMS) technology. The MEMS-based cooling engine array uses microfabricated structures with moving parts actuated by magnetic fields or electrostatic forces, eliminating the need for large mechanical compressors, valves, and seals. This substitution dramatically reduces system size, manufacturing cost, and mechanical noise while maintaining cooling capability.
Solution Approach 2:
The invention divides the cooling system into multiple independent cooling engines arranged in an array. Each cooling engine is a self-contained microdevice that can be fabricated using standard MEMS processes. The array of segmented cooling engines collectively provides the required cooling power, allowing scalability and modular design that reduces overall system complexity compared to a single large mechanical cooler.
2Device complexity
If conventional MEMS refrigerators are used, then miniaturization is achieved, but cooling power is relatively poor and cannot reach desired cryogenic temperatures under typical thermal loads
Solution Approach 1:
The patent merges multiple cooling engines into a single integrated array system where the cooling capacity scales with the number of engines. By combining numerous micro-scale cooling engines working in parallel, the system achieves macro-scale cooling power sufficient for cryogenic applications. The merged array provides both the miniaturization benefits of MEMS and the high cooling power of conventional systems.
Solution Approach 2:
The invention changes key operating parameters including the number of cooling engines in the array, the operating frequency of the MEMS actuators, and the working gas properties to optimize cooling power. By adjusting these parameters, the system can achieve cryogenic temperatures (below 120K) while maintaining adequate cooling power to handle typical thermal loads from infrared camera detectors.
3Reliability
If techniques to counteract mechanical vibration are applied, then sensor system performance degradation is reduced, but cooler complexity and manufacturing cost increase
Solution Approach 1:
The patent eliminates mechanical vibration at the source by replacing conventional mechanical actuators (motors, pistons, valves) with non-mechanical or minimally mechanical MEMS actuators. Magnetic field actuation and electrostatic actuation methods are used instead of rotating motors and reciprocating pistons, fundamentally reducing mechanical vibration and eliminating the need for complex vibration isolation systems.
Solution Approach 2:
The invention introduces magnetic fields as an intermediary to actuate the cooling engine components. Magnetic fields provide contactless actuation of the MEMS structures, eliminating mechanical connections and friction that generate vibration. This intermediary approach allows precise control of the cooling cycle without the mechanical noise and vibration inherent in traditional mechanical systems.
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 MEMS cryocooler achieves higher cooling powers and lower operating temperatures than conventional systems, enabling more accurate and reliable infrared imagery with reduced noise and mechanical interference, suitable for applications like infrared cameras.
Implementation Method 1
The surface area of each regenerator is sufficiently large to effectively transfer thermal energy to and from the working gas as it is passed through them
Implementation Method 2
Pairs of plane coil and magnetic region actuate two flexible diaphragms to expand the expansion space and compress the compression space
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
Techniques are disclosed for systems and methods using microelectromechanical systems MEMS techniques to provide cryogenic and/or general cooling of a device or sensor system. In one embodiment, a system includes a compressor assembly and MEMS expander assembly in fluid communication with the compressor assembly via a gas transfer line configured to physically separate and thermally decouple the MEMS expander assembly from the compressor assembly. The MEMS expander assembly includes a plurality of expander cells each including a MEMS displacer, a cell regenerator, and an expansion volume disposed between the MEMS displacer and the cell regenerator, and the plurality of cell regenerators are configured to combine to form a contiguous shared regenerator for the MEMS expander assembly.