Adaptive Flexible Sheet Interface for Prosthetic Pressure Fit
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Solution Overview
Problem
Current interfaces between rigid surfaces, such as those in prosthetic limbs, fail to accommodate changes in size and shape effectively, leading to uneven pressure distribution, skin problems, and the need for frequent replacement, which is impractical and costly.
Innovation Solution
A flexible sheet with a hollow chamber and a control circuit that adjusts fluid supply to change its surface area or volume in response to user movement and pressure changes, using sensors and a compressed fluid source to maintain contact and adapt to shape variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a soft interface material is used to fill the space between rigid surfaces, then pressure distribution is improved, but the interface fails when surfaces change size and shape frequently
Solution Approach 1:
The patent applies the dynamics principle by making the interface material itself dynamic through embedded hollow chambers that can inflate and deflate. This allows the interface to actively adapt its volume and shape in real-time to match changes in the rigid surfaces it contacts, transforming a static soft material into a dynamic system that maintains reliable contact despite frequent size and shape variations of the surfaces.
Solution Approach 2:
The patent implements parameter changes by modifying the volume of the hollow chambers within the interface material. By controlling the inflation and deflation of these chambers, the overall volume and shape parameters of the interface material can be dynamically adjusted to accommodate changes in the contacting surfaces, thereby maintaining effective pressure distribution and contact reliability.
2Stress or pressure
If the shape of rigid surfaces is designed to match, then pressure distribution is improved, but adaptability to size changes is lost
Solution Approach 1:
The patent resolves this contradiction by introducing dynamic adjustability to the interface material through controllable hollow chambers. This allows the interface to maintain its customised pressure-distributing shape while simultaneously adapting its overall size and volume to match changes in the rigid surfaces, combining the benefits of customised geometry with adaptability.
Solution Approach 2:
The patent applies preliminary action by pre-customising the shape of the interface material to optimally distribute pressure for a specific surface geometry. The embedded hollow chambers are then used to adjust the overall volume and dimensions of this pre-shaped interface, allowing it to adapt to size changes while preserving the beneficial pressure-distributing shape that was preliminarily designed.
3Reliability
If soft interface material is used, then contact between rigid surfaces is improved, but frequent replacement is required when surfaces change
Solution Approach 1:
The patent implements self-service by embedding controllable hollow chambers within the interface material, enabling it to automatically adjust its own volume and shape in response to changes in the rigid surfaces. This self-adjusting capability eliminates the need for manual intervention and frequent replacement, as the interface material can maintain effective contact continuously by adapting to surface changes on its own.
Solution Approach 2:
The dynamic nature of the hollow chambers allows the interface material to continuously adapt to surface changes, providing ongoing contact reliability without requiring replacement. The system transforms from a static material that degrades with surface changes into a dynamic system that actively maintains contact effectiveness throughout its service life.
4Adaptability or versatility
If cotton socks are used to accommodate size changes, then fit is improved, but sweating and friction increase
Solution Approach 1:
The patent applies pneumatics and hydraulics by using inflatable hollow chambers to accommodate size changes instead of absorbent textile layers. The chambers can be precisely inflated or deflated to match the dimensions of the contacting surface, providing a smooth, non-absorbent interface that reduces sweating and friction while maintaining adaptability to size variations.
Solution Approach 2:
The patent uses flexible hollow chambers as thin-film structures that can conform to the shape of the contacting surface while maintaining a smooth interface. These flexible shells provide the necessary adaptability to size changes without the textured, absorbent properties of cotton socks, thereby reducing harmful effects like excessive sweating and friction.
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 flexible sheet provides consistent support and pressure distribution, reducing the need for frequent replacements and improving the fit and comfort of prosthetic limbs by dynamically adjusting to changes in limb size and shape.
Implementation Method 1
a fluid source configured to supply a fluid to the hollow chamber via the opening to cause an increase in at least one of the surface area or the volume of the flexible sheet at the localised region
Data Source
AI summary
There is provided an apparatus comprising: a flexible sheet having a hollow chamber disposed within a thickness of the flexible sheet at a localised region of the flexible sheet, and an opening for transfer of a fluid between an exterior of the flexible sheet and the hollow chamber; a fluid source configured to supply a fluid to the hollow chamber via the opening to cause an increase in at least one of the surface area or the volume of the flexible sheet at the localised region; and a control circuit for controlling the fluid source; wherein the control circuit is configured to determine a control operation by identifying a category of movement of a user and/or predicting a required change in pressure in the hollow chamber; and wherein the control circuit is configured to implement the control operation by controlling the supply of fluid to or from the hollow chamber.