Electrostrictive Thermal Switch Stack for Electric Heat Flow Control
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Solution Overview
Problem
Existing thermal switches are limited in their ability to control heat flow over a wide temperature range, particularly at higher temperatures, and are typically restricted to thin-film materials.
Innovation Solution
A solid-state electrically controlled thermal switch utilizing an electrostrictive material with a stack configuration of alternating electrostrictive and conductive layers, allowing for the application of an electric field to alter thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional mechanical thermal switches are used, then thermal conductivity can be controlled, but the control mechanism is complex and not electrically controllable
Solution Approach 1:
The patent replaces mechanical control mechanisms with electrical field control. By applying an electric field to the electrostrictive material, the thermal conductivity is controlled without mechanical moving parts, achieving simpler electrical controllability while maintaining effective thermal switching functionality.
Solution Approach 2:
The patent changes the physical state of the electrostrictive material through electric field application, which alters the material's thermal conductivity parameter. This parameter change enables thermal switching without mechanical intervention, resolving the contradiction between ease of electrical operation and device complexity.
2Adaptability or versatility
If electric field control in ferroelectric materials is used, then thermal conductivity can be modulated, but the effect is limited to thin films and small temperature ranges
Solution Approach 1:
The patent uses composite structures combining electrostrictive materials with conductive layers in a stacked configuration. This composite approach enables the device to achieve effective thermal switching in thicker configurations beyond thin-film limitations, expanding adaptability to broader temperature ranges while maintaining manufacturability.
Solution Approach 2:
The patent transitions from two-dimensional thin-film geometry to a three-dimensional stacked configuration with alternating electrostrictive and conductive layers. This dimensional change allows the electric field effect to be distributed through multiple layers, achieving versatile temperature range control without being constrained to thin-film thicknesses.
3Reliability
If bulk materials are used, then phonon scattering by domain walls is reduced at low temperatures, but phonon-phonon scattering dominates at practical temperatures reducing the effect
Solution Approach 1:
The patent changes the material selection from conventional ferroelectric materials to electrostrictive materials, which exhibit different physical mechanisms. This parameter change in material properties enables effective thermal conductivity control at practical temperatures by utilizing electrostriction-induced lattice modifications rather than domain wall scattering, achieving reliability across broader operating temperature ranges.
Solution Approach 2:
The patent introduces conductive layers at specific positions within the stacked structure to enhance local heat transfer pathways. This local quality modification compensates for phonon-phonon scattering effects in the bulk electrostrictive material, maintaining reliable thermal conductivity control effectiveness across practical temperature ranges.
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 thermal switch achieves a 4 to 5 times larger effect of the electric field on thermal conductivity at room temperature compared to previous values, enabling efficient heat control over a broader temperature range.
Implementation Method 1
the electrostrictive material is operatively coupled to a third face of the plurality of faces... The first and second electrodes are configured to apply an electric field to at least a portion of the electrostrictive material... Applying the electric field to at least the portion of the electrostrictive material selectively alters a thermal conductivity of the thermal switch
Data Source
AI summary
Electrically controlled solid-state thermal switches and methods of controlling heat flow. An electrostrictive material is electromagnetically coupled to first and second electrodes that provide an electric field to the electrostrictive material. Different portions of the electrostrictive material are thermally coupled to each of a heat sink and a thermal load so that heat flowing from one into the other passes through the electrostrictive material. A control voltage is applied to the electrodes to selectively generate the electric field, thereby selectively altering the thermal conductivity of the electrostrictive material. The heat sink and thermal load are thereby selectively thermally coupled to each other in dependence on the control voltage.