US3929583A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for enumerating microorganisms
Assignee: Ministry of Health and Long Term Care
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Filing: 1975-08-14
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Granted: 1975-12-30
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Expires: 1995-08-14
Abstract
Abstract A membrane filter, adapted to retain microorganisms on its surface when a fluid sample is passed through it, has imprinted on said surface, in a gridded pattern, a barrier material which defines a plurality of microbial colony isolating cells that prevent colony spreading and confluence. Each cell has an area smaller than the normal colony size so that after incubation each existent colony is uniform in size and shape, and has high visiblity. The gridded filter facilitates colony detection and counting and makes possible high colony density counts. In one embodiment, the gridded filter is mounted in a container which is particularly suited for automated handling.
Inventors
- 👤 Anthony N Sharpe
- 👤 Gregory L Michaud
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:14
CPC Classifications
C; C12; C12M; C12M33/00; C12M33/14; C12M41/00; C12M41/30; C12M41/36; C12M47/00; C12M47/04
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
72 words
AN APPARATUS TO FACILITATE ENUMERATION OF MICROORGANISMS COMPRISING A MEMBRANE FILTER ELEMENT FOR RETAINING ON A SURFACE THEREOF THE MICROORGANISMS PRESENT IN A FLUID SAMPLE FILTERED THEREBY, SAID FILTER ELEMENT HAVING IMPRINTED ON SAID SURFACE, A BARRIER MATERIAL, WHICH RESTRICTS THE SPREAD OF COLONIES THROUGH ITS PHYSICAL PROPERTIES, IN A PATTERN DEFINING A PLURALITY OF ORDERED, MICROBIAL COLONY ISOLATING CELLS, WHEREIN THE CELLS ARE SMALLER IN AREA THAN THE NORMAL COLONY AREA.
Claim 2
Independent Claim
72 words
AN APPARATUS TO FACILITATE ENUMERATION OF MICROORGANISMS COMPRISING A MEMBRANE FILTER ELEMENT FOR RETAINING ON A SURFACE THEREOF THE MICROORGANISMS PRESENT IN A FLUID SAMPLE FILTERED THEREBY, SAID FILTER ELEMENT HAVING IMPRINTED ON SAID SURFACE, A BARRIER MATERIAL, WHICH RESTRICTS THE SPREAD OF COLONIES THROUGH ITS PHYSICAL PROPERTIES, IN A PATTERN DEFINING A PLURALITY OF ORDERED, MICROBIAL COLONY ISOLATING CELLS, WHEREIN THE CELLS ARE SMALLER IN AREA THAN THE NORMAL COLONY AREA.
Claim 3
Dependent Claim
12 words
The apparatus of claim 1 wherein the pattern is a rectangular grid.
Claim 4
Dependent Claim
16 words
The apparatus of claim 1 wherein the area of each cell is less than 25 mm2.
Claim 5
Dependent Claim
20 words
The apparatus of claim 1 wherein the width of barrier material for dividing the cells is greater than 0.025 mm.
Claim 6
Dependent Claim
15 words
The apparatus of claim 1 wherein the pattern penetrates the thickness of the membrane filter.
Claim 7
Dependent Claim
21 words
The apparatus of claim 1 wherein the barrier material is selected from the group comprising hydrocarbon wax, petrolatum and silicone wax.
Claim 8
Dependent Claim
12 words
The apparatus of claim 1 wherein the fluid sample is a liquid.
Claim 9
Dependent Claim
24 words
The apparatus of claim 1 wherein said membrane filter is mounted in a container comprising a surrounding frame portion and an apertured base portion.
Claim 10
Dependent Claim
20 words
The apparatus of claim 8 further comprising a nutrient retaining means disposed between the membrane filter and the base portion.
Claim 11
Dependent Claim
17 words
The apparatus of claim 8 wherein the frame portion is shaped for nesting with another similar container.
References Cited (Backward Citations)
US2761813A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |