Thermal Switch Using Moving Droplets for High Contrast
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Solution Overview
Problem
Current active thermal switches face challenges in achieving distinct thermal contrast, fast switching speeds, and simplified manufacturing processes, especially in small form-factors suitable for energy harvesting or cooling applications, due to inadequate thermal conductivity contrast and complex, costly materials.
Innovation Solution
The design incorporates an array of active thermal switches with a first substrate (active plate) and a second substrate (thermal contrast plate) separated by liquid droplets that move between conductive and insulative regions, utilizing spacers and electrodes for actuation, allowing for controlled thermal conductivity by selective positioning of droplets between thermally conductive and insulative regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If current active thermal switch approaches are used, then thermal management functionality is provided, but distinct thermal contrast between high heat conducting state and low heat conducting state cannot be achieved with small form-factors
Solution Approach 1:
The thermal switch is segmented into distinct thermally conductive regions and thermally insulative regions on the thermal contrast plate, allowing the droplet to move between these segmented zones to achieve high thermal contrast in a compact form-factor
Solution Approach 2:
Different regions of the thermal contrast plate are given different thermal properties (conductive vs. insulative), creating local quality variations that enable the droplet to modulate thermal conductivity by positioning itself over specific regions, achieving high thermal contrast in small size
2Speed
If current active thermal switch approaches are used, then thermal switching functionality is provided, but fast actuation speeds cannot be achieved at temperatures suitable for energy harvesting or cooling applications
Solution Approach 1:
The mechanical actuation system is replaced with an electric field-based actuation system using electrodes that interact with the conductive droplet, enabling fast switching speeds through electrical actuation rather than mechanical movement, while operating at suitable temperatures for energy harvesting and cooling applications
3Reliability
If many current thermal switch approaches are used, then thermal switching is achieved, but manufacturing processes are very complicated and materials are difficult to handle or expensive
Solution Approach 1:
The invention changes the material parameters by using a conductive liquid droplet instead of solid materials, and employs standard PCB fabrication techniques for the thermal contrast plate and electrodes, significantly simplifying the manufacturing process while maintaining reliable thermal switching performance
Solution Approach 2:
The invention uses inexpensive materials such as conductive liquids (which can be replaced if needed) and standard PCB materials, avoiding expensive and difficult-to-handle materials, thereby reducing manufacturing complexity and cost while achieving reliable thermal switching
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
This approach achieves high thermal contrast, low thermal resistance in the ON state, fast switching speeds, and cost-effective fabrication with no moving parts other than fluid droplets, enabling efficient thermal management in miniaturized formats.
Implementation Method 1
The droplet serves to connect the active plate with the thermal contrast plate through one or the other type of region. In FIG. 2, the electrodes received signals that caused the droplet to move away from the OFF electrode and towards the ON electrode.
Implementation Method 2
With the movement of the droplet to the thermally conductive region 18, heat will now conduct between the two plates through the droplet and thermally conductive region.
Data Source
AI summary
A thermal switch has a first substrate, a thermally conductive region on the first substrate, a thermally insulative region on the first substrate adjacent the thermally conductive region, a second substrate arranged adjacent the first substrate, a droplet of thermally conductive liquid between the first and second substrate adjacent the thermally conductive region and the thermally insulative region, and an actuator arranged on one of the first or second substrates to cause the droplet to move between the thermally conductive region and the thermally insulative region on the first substrate.