Non-Adhesive Vacuum Expander Rim for Low-Shear Tissue Expansion
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Solution Overview
Problem
Existing vacuum expanders for tissue enlargement, such as the Brava device, face challenges in maintaining vacuum integrity, balancing distractive forces with counter-forces to prevent capillary collapse, and reducing shear stresses at the skin-junction, leading to skin irritation and ulceration, particularly due to their adhesive nature and rigid rims.
Innovation Solution
The invention employs a deeply concave, tapered, soft rubber skirt with a non-adhesive, lubricated rim that deflects to conform to the body contour, increasing surface contact area and allowing the skin to glide freely, thereby preserving vacuum, balancing forces, and reducing shear stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an adhesive layer is used to seal the vacuum bladder with the skin, then vacuum integrity is improved, but skin irritation and ulceration occur due to adhesive wear and deterioration
Solution Approach 1:
The invention removes the adhesive layer entirely from the system. Instead of using adhesive to seal the vacuum bladder, the patent employs a mechanical sealing mechanism where the rim compresses soft tissue to create a seal, eliminating the harmful adhesive component that causes skin irritation and ulceration.
Solution Approach 2:
The invention introduces soft tissue (skin/fat) as an intermediary sealing element between the vacuum bladder and the external environment. The rim compresses this soft tissue to create a seal, using the body's own tissue as the mediating sealing component rather than relying on adhesive materials.
2Strength
If a rigid rim is used to anchor the vacuum device, then structural stability is improved, but shear stresses concentrate at the rim-tissue interface causing skin blistering and ulceration
Solution Approach 1:
The invention replaces the rigid rim with a flexible, compliant structure that can deform and distribute forces. The rim is designed to be soft and flexible, allowing it to conform to tissue contours and distribute mechanical loads evenly, preventing stress concentration and shear-related skin damage.
Solution Approach 2:
The invention changes the mechanical parameters of the rim from rigid to flexible. By altering the material properties and structural characteristics of the rim, the device achieves both structural stability and reduced shear stress through increased compliance and force distribution.
3Object-affected harmful factors
If the rim surface contact area is reduced, then shear stress is decreased, but counter-force becomes excessive causing capillary circulation collapse
Solution Approach 1:
The invention applies different local qualities to different parts of the rim structure. The portion of the rim in contact with the skin is designed to be soft and compliant to distribute pressure, while other portions maintain structural integrity. This spatial differentiation of material properties allows simultaneous reduction of shear stress and maintenance of adequate counter-force distribution.
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 effectively maintains vacuum seal, prevents excessive skin pressure, and significantly reduces shear stresses, making the device comfortable and safe for prolonged use without adhesive-related issues.
Implementation Method 1
an external vacuum source to apply a vacuum within the shell and impart a distracting force to expand tissue
Implementation Method 2
The rim is composed of rubber and has a lubricating layer on a bottom surface to glide over the skin, thereby reducing shear stress between the rim and contact surface of the skin
Data Source
AI summary
A tissue expander having a shell, an opening in the shell in communication with an external vacuum source to apply a vacuum within the shell and impart a distracting force to expand tissue, and a rim connected to the shell and adapted to be in contact with a skin of a patient. The rim is non-fixedly attached to the skin of the patient and moves laterally outwardly with respect to the shell under application of the vacuum.