Microbiological test device, assembly and method
View Patent ↗The device for microbiological testing of a sample of liquid includes an envelope and a filter membrane, the envelope including a removable body and a support for the membrane in the wetted state; the support including a sponge and the removable body including a flexible wall adapted to move toward the membrane, when the device is subjected to a reduced pressure and to return to its initial position when the 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 the sample between the inlet aperture and the outlet aperture of the device, of subjecting the device to a reduced pressure, of making the reduced pressure cease, and then of detecting the presence of microorganisms on the membrane of the device.
1. Device for microbiological testing of a sample of liquid flowing under pressure, including an envelope and a filter membrane 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, said envelope including a removable body and, inside said drainage volume, a support for supporting said membrane when wetted;
wherein:
said support include includes a relatively absorbent and flexible sponge; and
said removable body includes a flexible wall disposed against said sponge, 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.
2. Device according to claim 1 , wherein said support also include a porous sintered and relatively rigid member disposed between said membrane and said sponge.
3. Device according to either claim 1 or claim 2 , wherein said sponge is of polyvinylacetate.
4. Device according to claim 1 , wherein said removable body of said envelope is formed of said flexible wall.
5. Device according to claim 1 , wherein said flexible wall is a peelable film.
6. Device according to claim 5 , wherein said film is of polyethylene.
7. Device according to claim 1 , wherein said flexible wall holds said support in position inside said envelope.
8. Device according to claim 1 , wherein said flexible wall is sealed to said support.
9. Device according to claim 1 , wherein said device includes a first calibrated valve disposed between said inlet aperture and said receiving volume and a second calibrated valve disposed between said drainage volume and said outlet aperture, said valves being adapted to open in the direction of flow from said inlet aperture to said outlet aperture.
10. Device according to claim 1 , wherein a vent adapted to allow air to pass between the interior and the exterior of said envelope is formed in said envelope.
11. Device according to claim 1 , wherein said membrane, said sponge and said peelable film have closed contours.
12. Assembly for microbiological testing of a sample of liquid flowing under pressure including a device according to claim 1 and a clamp having clamping means adapted to hold said device in the manner of a vise by said flexible wall.
13. Assembly according to claim 12 , wherein said clamp has a fixed plate and a plate mobile between a rest position in which it is away from the device and a clamping position in which it bears against said device.
14. Assembly according to claim 13 , wherein the plate that bears on said flexible wall has a central cavity and in that said flexible wall of said device is also adapted to move away from said membrane within said cavity when said device is subjected to an increased pressure in said drainage volume and to return to its initial position when said increased pressure ceases.
15. A method for the microbiological testing of a sample of liquid flowing under pressure including:
a) the step of obtaining a device according to claim 1 ;
b) the step of passing said sample between the inlet aperture and the outlet aperture of said device;
c) the step of subjecting said device to a reduced pressure within the drainage volume of said device;
d) the step of making said reduced pressure cease; then
e) the step of detecting the presence of microorganisms on the membrane of said device.
16. A method according to claim 15 , further comprising, prior to step e), the step of passing a rinsing liquid between the inlet aperture and the outlet aperture of said device and then the implementation of steps c) and d) again.
17. A method according to any one of claim 15 or 16 , further comprising, prior to step e), the step of passing a nutritive liquid between the inlet aperture and the outlet aperture of said device and then the implementation of steps again.
18. A method according to any one of claim 15 or 16 , further comprising, prior to step e), the step of passing between the inlet aperture and the outlet aperture of said device a liquid adapted to reveal the presence of microorganisms by luminescence and then the implementation of steps c) and d) again.
19. A method according to any one of claim 15 or 16 , further comprising, prior to step e), the step of repeating steps c) and d) at least once.