Adjustable-Seal Diffusion Cell for Viable Skin Explants
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Solution Overview
Problem
Existing devices for studying percutaneous penetration and metabolism of substances in skin models suffer from issues such as tissue necrosis due to sealing pressures and fail to mimic in vivo conditions, leading to unreliable results and inability to jointly study passage and metabolism.
Innovation Solution
A diffusion cell design that maintains skin explants in survival mode with adjustable seals and controlled fluid circulation, ensuring sealing without necrosis and mimicking in vivo conditions, using adjustable seals and magnetic attraction for assembly, and controlled fluid flow to maintain explant viability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing pressure is increased to ensure sealing between compartments, then sealing reliability is improved, but tissue necrosis occurs and explant viability deteriorates
Solution Approach 1:
A flexible membrane is introduced as an intermediary element between the donor and receiver compartments. This membrane acts as a mediator that transmits sealing force while distributing it evenly across the explant surface, preventing localized high-pressure zones that cause necrosis. The membrane's flexibility allows it to conform to the explant surface while maintaining seal integrity.
Solution Approach 2:
The sealing mechanism transitions from direct rigid clamping to a distributed pressure system using a flexible membrane. This changes the pressure distribution parameter from concentrated high pressure to distributed low pressure, maintaining sealing force while reducing peak pressure below the necrosis threshold. The membrane material properties (elasticity, thickness) are optimized to achieve the required pressure distribution.
2Device complexity
If static incubation conditions are used, then device simplicity is maintained, but physiological relevance deteriorates due to lack of fluid circulation
Solution Approach 1:
A fluid circulation system is implemented to continuously flow medium through the receiver compartment, mimicking the continuous blood flow in vivo. This continuous action prevents substance accumulation, maintains metabolic waste removal, and sustains explant viability over extended periods. The circulation is achieved through a pump system that creates a closed-loop flow path.
Solution Approach 2:
A hydraulic circulation system is introduced where fluid flow is driven by pressure differential created by a pump. The system uses conduits and flow control elements to direct medium circulation through the receiver compartment. This hydraulic approach provides controllable, steady flow rates that physiologically relevant while maintaining system simplicity through standard pump and conduit components.
3Reliability
If Franz diffusion cells with clamping are used, then sealing is achieved, but explant survival is compromised due to tissue damage
Solution Approach 1:
A flexible membrane replaces the rigid clamping mechanism of traditional Franz cells. This thin film structure can deform to accommodate the explant surface while maintaining seal integrity. The membrane's flexibility prevents mechanical damage to the explant that would occur with rigid clamps, thereby extending explant survival time while preserving sealing function.
Solution Approach 2:
The sealing system transitions from a static rigid clamp to a dynamic flexible membrane that can adapt its shape and pressure distribution. The membrane dynamically conforms to the explant surface contours, maintaining optimal sealing contact without applying excessive localized pressure. This dynamic adaptation allows prolonged explant viability while ensuring continuous seal reliability.
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 skin explant viability and integrity, providing reliable results on percutaneous penetration and metabolism while minimizing leakage, thus improving the accuracy of skin model assessments.
Implementation Method 1
The seal is connected to the well in a housing made in the well and the other to the cap in a housing made in the cap, and that it includes means for adjusting the pressure exerted by the seals on the explant
Implementation Method 2
The invention relates to a device for the automated and simultaneous determination of the percutaneous passage and metabolism of a substance
Implementation Method 3
the interface means of the cap and the well are held against each other by a magnetic attraction force
Data Source
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AI summary
The invention concerns a diffusion cell comprising: an explant (250) of human/animal skin or reconstructed epidermis/skin; a well (220) comprising a cavity (320) constituting a receiving compartment; a cap (210) comprising a donor compartment (310); means for connecting the well and the cap; characterised in that the explant (250) is held between the donor compartment and the receiving compartment between two seals (271, 272), one of the seals (272) being connected to the well in a recess provided in the well and the other (271) to the cap in a recess provided in the cap, and in that it comprises means (211, 221) for adjusting the pressure applied by the seals (271, 272) to the explant (250). The invention also concerns a device implementing a plurality of cells of this type and making it possible to carry out automated samplings at defined time intervals.