Conformal Electromechanical Actuator Using Phase Change Material
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Solution Overview
Problem
Existing electromechanical actuators for portable, body-mountable applications require significant energy and time to provide high force and displacement, and they often lack flexibility, making them unsuitable for comfortable integration into garments or wearable devices.
Innovation Solution
A body-mountable device incorporating a heater and phase change material within a flexible enclosure, where the phase change material transitions from liquid to vapor upon heating, causing the enclosure to expand or increase pressure, allowing for quick, high-force actuation with minimal energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional electromechanical actuators are used to provide high force and displacement, then the actuation performance is improved, but the energy consumption and operation time increase significantly
Solution Approach 1:
The patent utilizes phase change material that transitions from liquid to vapor phase when heated by a low-power heater. This phase transition creates rapid volume expansion (approximately 1000x) that generates high force and displacement actuation. The phase change enables the system to achieve high actuation performance with minimal energy input from the heater, resolving the contradiction between force output and energy consumption.
2Force
If traditional electromechanical actuators are used to provide high force and displacement, then the actuation performance is improved, but the device size and complexity increase
Solution Approach 1:
The phase change material undergoes liquid-to-vapor transition within a simple sealed enclosure, generating high force through volume expansion without requiring complex mechanical components. This approach replaces traditional motors, gears, and linkages with a passive phase change system, dramatically simplifying device structure while maintaining high actuation force capability.
Solution Approach 2:
The patent employs a flexible enclosure that can expand and contract to accommodate the volume changes of the phase change material. This flexible shell design eliminates the need for rigid mechanical structures and complex actuation mechanisms, enabling high force generation within a simple, lightweight, and compact form factor suitable for wearable applications.
3Force
If traditional electromechanical actuators are used, then sufficient actuation force is achieved, but the device lacks flexibility and comfort for wearable applications
Solution Approach 1:
The flexible enclosure made of elastomeric or polymer materials allows the actuator to conform to curved body surfaces and move with the body. This flexibility enables comfortable integration into garments and wearable devices while maintaining the capability to generate sufficient actuation force through the phase change mechanism.
Solution Approach 2:
The phase change material provides high force generation within a flexible, compliant structure. The volume expansion during phase transition creates actuation force without requiring rigid mechanical components, enabling the device to be both powerful and adaptable to wearable applications.
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 solution enables rapid, high-displacement, and high-force actuation in a thin, flexible form factor, suitable for wearable devices, such as blood-pressure detecting cuffs, with improved comfort and efficiency.
Implementation Method 1
a phase change material that is in contact with the heater and that changes from a liquid phase to a vapor phase in response to being heated by the heater
Implementation Method 2
an increase in a volume of the enclosure such that the flexible material is displaced outward
Implementation Method 3
an increase in a pressure within the enclosure such that a force is transmitted, via the flexible material, to the external body surface
Data Source
AI summary
A variety of embodiments of an at least partially flexible actuator are provided. The actuator includes a phase change material contained within an at least partially flexible enclosure of the actuator. Application of heat, using a heater of the actuator, to the phase change material causes the phase change material to boil, increasing the volume of the actuator and/or increasing a pressure within the actuator. As a result, the actuator can be used to apply a force to objects in an environment of interest. The actuator could be incorporated into a wearable blood pressure cuff and used to apply pressure to a body part of a wearer in order to detect a blood pressure of the wearer. In other examples, the actuator could be incorporated into a wearable device and used to secure a sensor or other elements of the device against skin of a wearer.