|Publication number||US3785928 A|
|Publication date||Jan 15, 1974|
|Filing date||Jan 27, 1971|
|Priority date||Jan 27, 1971|
|Publication number||US 3785928 A, US 3785928A, US-A-3785928, US3785928 A, US3785928A|
|Original Assignee||M Kessler|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (21), Classifications (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Y A R T N O I m R Ln 5T s L m m AU L 0 I R E T C A B Filed Jan.
INVENTOR Milton Kass/er ATTORNEY United States Patent 3,785,928 BACTERIOLOGICAL TITRATION TRAY Milton Kessler, 6690 Harrington Ave., Youngstown, Ohio 44512 Filed Jan. 27, 1971, Ser. No. 110,108 Int. Cl. C12k N US. Cl. 195-140 2 Claims ABSTRACT OF THE DISCLOSURE A molded plastic titration tray containing a large number of small open test cups serving as individual test tubes and which are integral with the tray and project downwardly from the tray except for a lip at the top of each cup which projects above the surface of the tray to prevent serum or solution spilled on the tray surface from contaminating the tray contents of the cup. In one modification there is a small hole in the bottom of each cup, small enough so that surface tension prevents the fluid contents of the cup from flowing through the hole, but the contents can be discharged at will by applying a sonic probe or air pressure to the cup.
Many standard laboratory procedures in both biological research and medical laboratories require the use of large numbers of test tubes in each of which a small sample of fluid material is placed for test purposes. A common device for such use is a titration tray, which is typically a small plastic tray measuring approximately four by six inches, and containing a number of rows of small cups projecting downwardly from the tray surface, typically eight rows of twelve cups each. These are used in place of test tubes for assaying virus, measuring antibodies and tissue culture, serum dilutions, and many types of spot tests. In use, a small amount of each solution being tested is dropped into each cup by means of a pipette or medical dropper or similar device, and it is, of course, important that these solutions be kept entirely independent of each other, as even a trace of contamination from one solution to another will invalidate the test results. With the present type of tray, if there is any carelessness in filling the cups, so that one overflows, this overflow will spread on the surface of the tray to adjacent cups, thereby contaminating them. This problem is solved, according to the present invention, by providing a raised lip around each cup, so that material spilled on the surface of the tray cannot readily enter adjacent cups. It is also desirable for some testing purposes to transfer the contents of individual cups to other cups in a different tray, and the present invention provides a novel method for expeditiously doing this by means of a small hole in the bottom of each cup, too small to normally permit the contents to flow through the hole because of the surface tension of the liquid; by applying a sonic or ultra-sonic prove to the individual cups, or by applying air pressure to the individual cups, the surface tension can be broken and the contents made to flow readily through the small aperture into another cup placed below the first cup. This can be done either to the entire contents of a tray, each cup pouring its contents into another cup in a similar tray placed below the first, or else can be done to individual cups selectively.
The specific nature of the invention, as well as other objects and advantages thereof, will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing, in which:
FIG. 1 is a plan view of a titration tray showing a typical arrangement of the cups; and
FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, showing both types of cups and also a typical stacking arrangement for the trays.
Referring to the drawings, a standard form of titra- 3,785,928 Patented Jan. 15, 1974 tion tray 2 is made of clear plastic having 96 cups 3 arranged in eight rows of twelve cups each, and typically provided with numbers 1 12 to designate the vertical rows and letters A, B H to indicate the horizontal rows, whereby the location of any individual cup can be designated by the combination of a number and a letter. The entire tray is preferably formed by an injection molding operation, the technique of which is well known. The entire tray is usually only about four by six inches in size, and the individual cups are in the order of 0.25 inch diameter by approximately A inch deep. One novel feature of the present tray is that each individual cup 3 is provided with a raised rim 4 which extends above the surface 2 of the tray. While :a careful operator can usually fill each cup individually without spillage, sometimes there is a slight overfilling, and a small amount of the material then spills out onto the surface 2 of the tray. In the known types of tray, where the cup is flush with the surface of the tray, there is nothing to prevent this material as it spreads from spilling over into an adjacent cup, with resultant contamination which may spoil the test being made. The raised lip 4 of the present cups minimizes this possibility, as a small amount of spillage may spread somewhat on the surface of the tray, but will not enter into the adjacent cups because of the raised lips. For standard usage, the upper and lower trays shown in FIG. 2 are identical, except that the upper set is provided with a perforation of approximately pinhole size in the bottom, while the lower set is unperforated. The pinholes are sufliciently small so that the fluid 7 disposed in the cup 3 will not flow through the pinhole normally, because of the surface tension of the fluid. However, if a high frequency vibrating device such as an ultra-sonic probe 8, which is a known device used in spot welding of plastic materials, is applied to the rim 4 of the cup 3, the resultant vibrations will cause the contents of the cup to be discharged into any suitable container, which will usually be a similar tray placed beneath the tray having the perforated cups. The trays are provided with side walls 9 having lips 11 so that they can be stacked one above the other, whereby the contents of each cup will be dis charged into the correspondingly numbered cup of the lower tray. The lower tray may have imperforated cups, or if desired, may also contain perforate cups for subsequent discharge of the contents into still another container.
For use with the ultra-sonic probe, the perforate-cup trays should preferably be made of a fairly hard plastic material so that the sonic vibrations will be transmitted through the material. If the entire tray is made of such material, all of the contents of the cups can be simultaneously emptied into a lower tray or any other desired container; however, for many test purposes, it may be desirable to empty the contents of the cups individually, and for this purpose, the individual cups 3 are preferably made of a relatively rigid plastic material, as indicated by the section lines in FIG. 2, while the rest of the tray is made of a softer and deaded plastic material so that it will not transmit vibrations, whereby when the probe is touched to each individual cup it can be emptied without affecting the adjacent cups due to the vibration insulating qualities of the softer plastic material. This can be readily accomplished by dual-injection techniques which are known in the art whereby different materials may be simultaneously molded to produce a unitary object having both soft and hard portions.
Another way of emptying individual cups is to use a pressure bulb 12 having a soft rubber or rubber-like tube of the proper diameter to encompass individual cups, whereby a slight finger pressure on the bulb 12 will produce a suflicient increase in air pressure on the top of the fluid contained in the cup so that it is immediately emptied through the aperture 6 into the lower cup or container.
Particularly in the case where the trays are made of a single material, this may be a very thin plastic sheet material, which enables the entire tray to be made so inexpensively that it can be thrown away after each use, thus disposing of any need for sterilizing between uses. If the trays are to be re-usable, then they will be made of heavier construction and a more rigid material which can stand the sterilizing temperatures which may be necessary. It is apparent that the pinhole in the cup has utility apart from the lip.
1. A bateriological titration tray formed of a single sheet of plastic material having (a) a flat horizontal tray-surface having a number of small test cups which are integral with the tray surface and which project generally downwardly from the tray surface,
(b) said sheet around the mouth of each said cup having a raised lip at the top of each cup, which lip projects above the surface of the tray to prevent liquid spilled on the tray surface from readily spreading over said surface into said cups,
(c) wherein at least some of said cups have a small pinhole perforation at the bottom,
(d) said pinhole perforation being sufliciently small so that surface tension will normally prevent fluid in said perforated cups from flowing out through the perforation, but large enough so that when the surface tension is broken, the fluid will flow through the pinhole.
2. A bacteriological titration tray having (a) a flat tray surface of sheet material having a number of small open test cups which are integral with the tray surface and project generally downwardly from the tray surface,
(b) wherein at least some of said cups have a small pinhole perforation at the bottom,
(0) said pinhole perforation being sufficiently small so that the surface tension will normally prevent fluid in said perforated cups from flowing out through the perforations, but large enough so that when the surface tension is broken, the fluid will flow through the pinhole.
References Cited UNITED STATES PATENTS 3,356,462 12/1967 Cooke et al 195139 LE 3,649,464 3/1972 Freeman 195-140 A. LOUIS MONACELL, Primary Examiner R. J. WARDEN, Assistant Examiner US. Cl. X.R. 23-292; -139
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|US20050019225 *||Aug 16, 2004||Jan 27, 2005||Sanadi Ashok Ramesh||Method and apparatus for preventing cross-contamination of multi-well test plates|
|WO1981000063A1 *||May 14, 1980||Jan 22, 1981||Minnesota Mining & Mfg||Disposable microbial profile tray|
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|WO1998055232A1 *||Jun 3, 1998||Dec 10, 1998||Corning Incorporated||Multiwell plate volume adaptor|
|U.S. Classification||435/305.3, 422/510|
|International Classification||B01L3/02, C12M1/20|
|European Classification||B01L3/02C, C12M1/20|