Cannula TCP Actuator With Internal Heating for Low-Power, Fast Response
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Solution Overview
Problem
Existing electrothermal actuators require high power, have limited actuation frequency, and involve complex fabrication processes, while hydraulic and pneumatic actuators are bulky and impractical for miniaturized applications.
Innovation Solution
A cannula TCP actuator is fabricated by inserting a resistive heating wire into a polymer microtube, twisting and coiling it, and annealing the assembly to create a twisted and coiled tube that generates tensile actuation when powered electrically, with the heating wire inside the microtube for efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional electrothermal actuators are used, then actuation function is achieved, but power consumption is high and actuation frequency is limited
Solution Approach 1:
The heating wire is inserted inside the polymer microtube, creating a nested structure where the heating element is contained within the actuator body. This nested configuration improves thermal coupling efficiency, allowing faster heat transfer to the polymer material, thereby enabling higher actuation frequencies while reducing the power required to achieve the same thermal effect.
Solution Approach 2:
The patent changes the physical configuration parameter by transitioning from external heating to internal heating (inserting the heating wire inside the microtube). This parameter change optimizes the thermal transfer path, reducing thermal resistance and enabling faster response times and higher actuation frequencies at lower power consumption.
2Reliability
If special coating is applied on actuator surface, then actuation performance is improved, but fabrication complexity and cost increase
Solution Approach 1:
The patent extracts the need for special surface coatings by implementing internal heating through the inserted heating wire. This eliminates the requirement for complex surface treatments or coatings, simplifying the fabrication process while maintaining or improving actuation performance through more efficient thermal coupling from the interior.
3Force
If hydraulic or pneumatic actuators are used, then actuation force is achieved, but device size becomes bulky and impractical for miniaturization
Solution Approach 1:
The patent replaces the mechanical hydraulic or pneumatic systems with an electrothermal system. By using electrical heating to induce thermal expansion or contraction of the polymer microtube, the actuator achieves mechanical actuation force without requiring bulky fluid reservoirs, pumps, or compressors, enabling miniaturization while maintaining actuation capability.
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 cannula TCP actuator achieves lower power consumption, higher operational frequency, and efficient energy transfer, enabling micro-level actuation with frequencies up to 1 Hz and power in the milliwatt range, and can be fabricated in under 3 minutes.
Implementation Method 1
applying an electrical power to a resistive heating wire in the cannula TCP actuator to cause the cannula TCP actuator to contract
Implementation Method 2
annealing the microtube assembly to form the cannula TCP actuator
Data Source
AI summary
Technology disclosed herein provides a cannula TCP actuator comprising an annealed microtube assembly including a polymer microtube having inserted therein a resistive heating wire such that the resistive heating wire extends through the length of the polymer microtube, wherein the microtube assembly is arranged in a twisted and coiled tube. The cannula TCP actuator is fabricated by inserting a resistive heating wire into the polymer microtube, forming a microtube assembly by applying a longitudinal force to a first end of the polymer microtube in a direction parallel to a center axis of the polymer microtube and in an opposite direction relative to a second end of the polymer microtube, and applying a rotational force to the second end of the polymer microtube during application of the longitudinal force to cause the polymer microtube to twist and coil about the center axis, and annealing the microtube assembly.