Flexible Sponge Microbiological Test Device for Liquid Purging
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Solution Overview
Problem
Conventional microbiological testing devices under pressure face challenges with imperfect purging operations due to the bubble point phenomenon, where residual liquid is not effectively drained, leading to unstable and non-repeatable results, and the rigid porous pad stores excess liquid that cannot be eliminated even with strong vacuum.
Innovation Solution
The device incorporates a flexible sponge and a peelable polyethylene film that moves towards the membrane under reduced pressure to expel residual liquid, and returns to its initial position to absorb and collect remaining liquid, combined with a porous sintered member for mechanical support, allowing for effective purging and homogeneous moisture distribution on the membrane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid porous pad is used to support the membrane and drain liquid, then the membrane is supported when wetted and liquid can be drained, but excess residual liquid is stored in the pad and cannot be eliminated even with strong vacuum
Solution Approach 1:
The patent replaces the rigid porous pad with a flexible membrane that can deform under pressure. This flexible membrane maintains structural support for the filter membrane while allowing complete evacuation of residual liquid through vacuum, as it can be compressed to expel trapped liquid without maintaining liquid storage capacity like rigid porous materials.
Solution Approach 2:
The patent changes the physical state and mechanical properties of the support structure from rigid to flexible. By using a flexible membrane with specific elastic properties, the system transitions from a state where liquid is trapped in porous structures to a state where the support structure can deform to facilitate complete liquid evacuation while maintaining membrane support.
2Productivity
If vacuum is applied to purge liquid from the device, then liquid is aspirated and drained out, but when membrane surfaces contact air, the membrane behaves like an airtight film preventing gas bubbles from escaping (bubble point phenomenon)
Solution Approach 1:
The patent applies vacuum pressure before the membrane becomes completely wetted and before the bubble point phenomenon occurs. By initiating the vacuum purging operation at the appropriate stage in the filtration process, the system evacuates liquid from the drainage chamber and flexible membrane before air contact causes the membrane to seal its pores, ensuring complete liquid removal without encountering the airtight barrier effect.
3Productivity
If liquid is expelled to the outlet aperture along preferential paths during purging, then some liquid is drained, but regions remain that cannot be purged leading to unstable and non-repeatable results
Solution Approach 1:
The patent uses a flexible membrane that dynamically responds to pressure changes during purging. As vacuum is applied, the membrane deforms and reconfigures the flow paths in real-time, preventing the formation of stable preferential channels. This dynamic adaptation ensures uniform liquid evacuation across all regions of the drainage chamber, eliminating dead zones and making the purging process repeatable and reliable.
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
This solution enables efficient purging of the membrane, ensuring optimal conditions for microorganism growth or detection by eliminating excess water and preventing reagent dilution, with the flexible components allowing for repeated use and high-pressure resistance.
Implementation Method 1
said support means include a relatively absorbent and flexible sponge
Implementation Method 2
The liquid then passes through the membrane which rests in face-to-face contact on the sponge
Implementation Method 3
said flexible wall being adapted to be moved toward said membrane when said device is subjected to a reduced pressure inside said drainage volume and to return to its initial position when said reduced pressure ceases
Implementation Method 4
when the pressure inside the device returns to normal, the flexible wall returning to its initial position releases the sponge
Implementation Method 5
The porous sintered member 4 is supported via the sponge disk 5 by a polyethylene film 6
Implementation Method 6
a filter membrane (3) inside said envelope, said membrane subdividing the internal volume of said envelope into a liquid receiving volume communicating with an inlet aperture, and into a liquid drainage volume communicating with an outlet aperture
Data Source
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AI summary
The device for microbiological testing of a sample of liquid includes an envelope (11) and a filter membrane (3), said envelope (11) including a removable body (6) and means (4, 5) for supporting said membrane (3) in the wetted state; said supporting means (4, 5) including a sponge (5) and said removable body including a flexible wall (6) adapted to move toward said membrane (3), when said device is subjected to a reduced pressure and to return to its initial position when said reduced pressure ceases. The assembly includes a device of the above kind and a clamp adapted to grip the device in the manner of a vise. The method includes the step of obtaining such a device, of passing said sample between the inlet aperture and the outlet aperture of said device, of subjecting said device to a reduced pressure, of making said reduced pressure cease, and then of detecting the presence of microorganisms on the membrane of said device.