Shape-Matching Cushion Cells for Uniform Pressure Support
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Solution Overview
Problem
Individuals confined to bed or wheelchair are at risk of tissue breakdown due to uneven blood flow and pressure distribution, leading to ischemic sores, as conventional support surfaces apply non-uniform forces that reduce blood flow to specific areas.
Innovation Solution
A molded foam cushion with an array of suspension elements, each having a load-bearing surface, end walls, and an optional bottom wall with a vent, arranged in a pattern where longitudinal axes are at right angles, providing a displaceable surface that exerts a constant restoring force, ensuring uniform pressure distribution and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional support surfaces are used, then they provide basic support, but they apply non-uniform forces that reduce blood flow to specific areas
Solution Approach 1:
The cushion is divided into an array of individual suspension elements (cells) that can independently deform and provide support. Each cell acts as a separate support unit, allowing the cushion to adapt to irregular body contours while distributing pressure uniformly across multiple contact points, thereby preventing localized tissue breakdown.
Solution Approach 2:
The suspension elements have varying properties (different volumes, orientations, and positioning) to provide locally optimized support. Elements are positioned and sized to match specific body regions, ensuring that each area receives appropriate uniform supporting forces tailored to its anatomical characteristics.
2Shape
If the load-bearing surface deforms to match body contours, then it conforms to irregular shapes, but the restoring force varies with deformation extent
Solution Approach 1:
The suspension elements are designed with specific geometric parameters (arch-like cross-section, controlled wall thickness distribution, vent opening dimensions) that enable them to maintain a substantially constant restoring force throughout their deformation range. The material thickness of the load-bearing surface is greater than the end walls, allowing controlled buckling that stabilizes the restoring force during deformation.
Solution Approach 2:
The load-bearing surface of each suspension element has a generally arch-like cross-sectional configuration with curved geometry. This curved structure facilitates controlled buckling behavior that helps maintain constant restoring force during deformation, as the arch shape distributes stresses more uniformly throughout the element.
3Ease of manufacture
If the end walls have the same thickness as the load-bearing surface, then manufacturing is simpler, but they cannot distend outwardly when force is applied
Solution Approach 1:
The suspension elements have non-uniform wall thickness distribution, with the load-bearing surface having greater thickness than the end walls. This localized variation in thickness allows the end walls to distend outwardly when force is applied to the load-bearing surface, providing adaptability while maintaining structural integrity where needed.
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 cushion minimizes tissue deformation and enhances blood flow by maintaining uniform supporting forces across irregular body contours, reducing the risk of tissue breakdown and promoting oxygenation.
Implementation Method 1
The optional bottom wall has a vent opening formed therein of a predetermined size that allows controlled release of air from the chamber when force is applied to the load bearing surface to control collapsing of the cell
Implementation Method 2
The surface of the cushion is displaceable that, when deformed, exerts a restoring force that is generally constant irrespective of the extent of the deformation
Data Source
AI summary
A cushion comprising an array of individual suspension elements arranged in a pattern wherein one embodiment the longitudinal axis of each suspension element in the array is positioned at a right angle or parallel to the longitudinal axes of the adjacent suspension elements. Each suspension element has a displaceable load-bearing surface, a first end wall, a second end wall, and an optional bottom wall, with load-bearing surface and recited walls defining an inner chamber. The material thickness of the load-bearing surface generally is greater than the material thickness of the end walls whereby the end walls deflect outwardly toward the load-bearing surfaces of adjacent support elements under load. The load-bearing surface can have a substantially arch-shaped, elliptical or rectangular cross-section and may be constructed from different materials to make a composite suspension element. The bottom wall of the suspension element may have a small vent opening of a predetermined size to allow a controlled release of air from the inner chamber under load to enhance the viscous feel of the cushion. The cushion also includes a cover enclosing the array of suspension elements.