Thermo-Electric Prosthetic Limb Actuation for Lightweight Digit Control
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Solution Overview
Problem
Conventional prosthetic arms are too heavy and unwieldy, leading to user fatigue and lack of fine motor control due to the weight distribution and added components like batteries, which can cause repetitive compensatory movement patterns and injuries.
Innovation Solution
A prosthetic apparatus utilizing thermo-electric actuators with Nitinol strands, connected to digits via cables, that retract and extend based on thermal activation, allowing for lightweight and efficient actuation with a biasing structure to return to a resting position, powered by a low-energy power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional prosthetic arms use traditional actuators and power systems, then the prosthetic can perform basic movements, but the weight and size increase significantly
Solution Approach 1:
The patent replaces traditional motor-based actuation systems with a thermal field-based system. Thermal actuators utilize thermal expansion and contraction of materials (such as shape memory alloys) to generate mechanical motion, eliminating the need for heavy motors, gears, and traditional power trains. This substitution dramatically reduces the weight of the prosthetic arm while maintaining the ability to perform precise digit movements.
Solution Approach 2:
The invention changes the operating parameters from mechanical (torque, power, rotational speed) to thermal (temperature, heat transfer). By controlling the temperature of thermal actuators, the system achieves precise control over digit movement without requiring the heavy mechanical power systems traditionally needed for prosthetic actuation. This parameter transformation enables lightweight construction while preserving functional capability.
2Use of energy by moving object
If conventional prosthetics include batteries and power systems, then the prosthetic can be powered, but the weight increases and user fatigue worsens
Solution Approach 1:
The patent replaces electrical motor systems with thermal actuation systems. Thermal actuators convert thermal energy directly into mechanical motion through material property changes (thermal expansion, shape memory effects), eliminating the need for heavy electrical motors, power electronics, and large batteries. This substitution dramatically reduces the overall weight of the prosthetic arm while maintaining operational capability.
Solution Approach 2:
The invention utilizes phase transitions in thermal materials (such as the martensitic transformation in shape memory alloys) to generate mechanical motion. These phase transitions occur in response to temperature changes and provide a direct conversion from thermal to mechanical energy, bypassing the need for heavy electrical power systems and batteries traditionally required for prosthetic actuation.
3Weight of moving object
If conventional prosthetic arms are made lighter, then user fatigue decreases, but the structural integrity and durability may be compromised
Solution Approach 1:
The patent employs composite materials that combine lightweight properties with high strength characteristics. Thermal actuators and structural components utilize materials such as shape memory alloys, carbon fiber composites, and other advanced materials that provide high strength-to-weight ratios. These composite materials enable the prosthetic arm to be significantly lighter than conventional designs while maintaining the structural integrity and durability required for safe operation.
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 provides a lighter prosthetic arm with improved user ergonomics, reduced fatigue, and enhanced fine motor control through efficient energy use and anatomically similar digit movements.
Implementation Method 1
a first charge plate and a second charge plate positioned within the internal volume; a Nitinol band disposed within the internal volume and having opposing ends electrically coupled to the first charge plate and the second charge plate, respectively
Implementation Method 2
a Nitinol band disposed within the internal volume... the Nitinol band includes a helical coil positionally offset from the casing by a gap; and while maintaining the gap relative to the casing, the helical coil is configured to rotate and compress in response to thermal activation of the Nitinol band
Implementation Method 3
the casing includes a thermally conductive material configured to dissipate heat from the Nitinol band into an environment external to the casing
Data Source
AI summary
A prosthetic apparatus can include: a limb connection portion attachable to a user; a hand portion opposite the limb connection portion, the hand portion including digits; and thermo-electric actuators positioned between the hand portion and the limb connection portion, the thermo-electric actuators connected to the digits.