IMPROVED BIOMEDICAL ANALYSIS TRAY

Abstract: An improved biomedical analysis tray (10) for use in electromagnetic radiation-beam instrumental or visual analysis of multiple samples. The tray includes a planar upper plate (12) including ninety-six circular apertures (16) arrayed therethrough in eight rows and twelve columns. A sample well (18) depends from each aperture. Each well (18) has a right cylindrical segment (22), a truncated conical segment (24), and a circular flat bottom panel (20). The upper plate (12) is supported by support walls (14) of sufficient height to maintain the bottom of the sample wells (18) in free suspension. The tray (10) is constructed of a radiation rigid material transparent to the analysis radiation and which is impervious to the reagents and organic agents utilized in the desired analyses.

Description: IMPROVED BICMEDICAL ANALYSIS TR&Y BACKGROUND OF THE INVENTION Field of the Invention The present invention relates generally to chemical and biological analysis apparatus and more specifically to apparatus for light-based analysis of multiple solution reactions. Description of the Prior Art Biomedϊeal facilities, such as hospital laboratories, frequently run large numbers of tests on organic samples such as blood or urine. These tests are utilized to identify the presence or absence of bacterial or viral organisms, the genus/species identification of bacterial or viral organism and/or the anti- microbial agent susceptibility of the bacterial or viral organisms within the sample. Standardized tests have been developed over the years for rapid and consistent analysis of these samples. One of the types of analysis run on organic samples utilizes reactions of varying concentrations of the sample with known antimicrobial agents and/or other biochemical agents. Depending on the presence or absence of specific substances or organisms and the metabolic activity of such organisms a precipitate or other opaque deposit such as a bacterial growth may be formed in the solutions. This opaque deposit may then be visually observed. The technician may determine whether the specific test has been positive or negative by the absence or presence of the opaque deposit growth. Initially, analysis of this sort was done in test tubes arrayed in racks. However, improved techniques and cost pressures have resulted in the miniaturization of the tubes to small transparent sample wells in a tray structure. Each tray is designed for analysis of a single sample or multiple samples and includes stations for analysis of various concentrations of the sample of antimicrobial agents and biochemical substrates in addition to Λ. WIPO including wells for other purposes. A standard type of sample tray utilized in biomedical facilities has ninety-six wells, arranged in eight rows and twelve columns. Each well is generally cylindrical and is supported such that the bottom surface does not rest upon the counter or other surface upon which the tray is set. The design of the prior art wells has been generally restricted to three distinct types of well shapes. The wells utilized have been predominately cylindrical in shape due to the ease of cleaning. The bottom portions of the wells have been either gently rounded in a hemispheric shape, totally flat bottomed or tapered to a point. Each of these types of wells has proven acceptable for visual analysis of the samples for the presence of absence of opaque deposits. However, each has significant disadvantages when the trays are used for instrumental examination. The purely flat bottomed wells allow the opaque deposits to collect across the entire surface of the bottom and in such situations the deposit is often too widely dispersed to provide sufficient opacity to trigger the instru¬ ment used for analysis. Both the hemispheric and conical bottoms allow the opaque deposits to goϋeet at the bottom center of the well and thus provide sufficient opacity for visual or instrumental analysis. However, both of these types of wells, by their very shape, provide optical diffraction of the analysis beam and denegrate the quality of instrumental analysis. Consequently, no prior art tray has been entirely successful for use in automatic instrumental optical analysis of multiple samples. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved biomedical analysis tray for use with instrument optical analysis. Briefly, a preferred embodiment of the present invention includes a support structure supporting a planar upper plate including ninety-six circular apertures therethrough arrayed in eight rows and twelve columns, each aperture including a well depending therefrom. Each well includes a right cylindrical segment adjacent to the aperture and a truncated conical segment at the O PI ^ bottom of the right cylindrical segment. The truncated conical section culminates at the bottom of the well with a circular flat bottom panel having a radius less than the radius of the aperture. The support structure is sufficient to prevent the bottoms of the wells from contacting a planar surface when the tray is set upon such. The entire improved biomedical tray is constructed of a rigid transparent material. It is an advantage of the present invention that the truncated conical segment urges the opaque deposit to become concentrated upon the flat bottom panel, thus resulting in improved instrumental analysis. It is another advantage of the present invention that the flat bottom panel is amenable to perpendicular radiation beam analysis with an insignificant amount of diffraction. It is a further advantage of the present invention that the amount of errors in instrumental analysis is significantly reduced by the improved design. These and other objects and advantages of the present invention will become clear to one skilled in the art upon reading the detailed description of the preferred embodiment which is illustrated in the several figures of the drawings. IN THE DRAWING Fig. 1 is a top plan view of an improved biomedial analysis tray according to the present invention; Fig. 2 is a side elevational view of the tray of Fig. 1; Fig. 3 is a side elevational view of an individual well of the trayj and Fig. 4 is a schematic illustrating the manner in which instrumental analysis takes place with the well of Fig. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is an improved biomedical analysis tray for use particularly with instrumental optical analysis devices. The tray is adapted for use in biomedical facilities such as hospital laboratories wherein it is necessary to analyze a large number of samples. The tray is used for electromagnetic radiatϊon beam (usually visible light) instrumental detection of precipitates bacterial growth cultures or other opaque deposits caused by the reaction of samples of biological ϊnoculumns with antimicrobial agents or other biochemical substrates. A preferred embodiment of the present invention is illustrated in a top plan view in Fig. 1. The improved biomedial analysis tray 10 includes a planar upper plate 12. Upper plate 12 is rectangular in shape and is supported on each side by a predominantly vertical support wall 14. Support wall 14 maintains plate 12 above and parallel to a support surface such as a table top or counter top when the tray 10 is set upon such a surface. The plate 12 is formed to includes a plurality of apertures 16 there¬ through. The preferred embodiment includes ninety-six such apertures 16 arrayed in eight rows and twelve columns. A sample well 18 for receiving samples for analysis depends from each aperture. Each sample well includes a circular flat bottom panel 20. Referring now to Fig. 2, a side elevational view of the improved biomedical analysis tray 10 is shown. Since the tray 10 and all the parts thereof are constructed of transparent material the construction details of the tray are visible through the near support wall 14 in this view. The illustration of Fig. 2 shows the relationship between the bottom of the support walls 14 and the bottom of the wells 18. It is necessary that the bottom panels 20 of the wells 18 be supported such that they are not scratched or otherwise damaged by direct contact with a flat surface such as a counter upon which the tray 10 is placed. The specific structure of the sample well 18 is illustrated in Fig. 3. The circular aperture 16 which is formed in support plate 12 provides the upper opening to the sample well 18. Sample well 18 then includes a right cylindrical segment 22 extending downward from the aperture 16. At the bottom of the right cylindrical segment 22 is formed a truncated conical segment 24. At the bottom of truncated conical segment 24 is the flat bottom panel 20. The sample well 18 is constructed including a well wall 26 for retaining the sample within the well 18. The interior surface of the well wall 26 in the right cylindrical segment is vertical and smooth such that precipitates cultures, or other deposits will not readily adhere to the well wall 26 but will settle to the bottom of the well 18. In the truncated conical segment 24 the well wall 26 is slanted inward to urge precipitates or other deposits to slide down the interior surface of the well wall 26 and come to rest on the flat bottom panel 20. Fig. 4 illustrates the manner in which the sample well 18 of the preferred embodiment is utilized for instrumental optical analysis. When an analysis is to be done in a given sample well 18, the sample, such as a biological inoculum, and the reagent, such as an antimicrobial agent or other biochemical substrate are combined in the sample well 18 to form a composite liquid 28. The liquid content 28 is allowed to react within the sample well 18 for a predetermined time period, usually three to orty hours, such that if the proper conditions are present, a precipitate bacterial or viral growth or other opaque deposit 30 will form and will settle to the bottom of the sample well 18. The construction of the sample well urges the precipitate 30 to settle upon the upper surface of the flat bottom panel 20. Since the upper surface of flat bottom panel 20 is relatively small in area, the precipitate 30 is formed to a maximal thickness such that maximum electromagnetic radiation impedance for a given amount of precipitate 30 is achieved. At this stage a technician may perform a visual analysis on the sample well 18 to determine whether a precipitate 30 has or has not been formed. Since the precipitate 30 is concentrated on the flat bottom panel 20, this analysis is easily done. However, in many cases, the analysis of the samples in tray 10 is instrumentally accomplished. In this process, an electromagnetic radiation source 32 within the instrument emits radiation 34. In the ordinary case, radiation source 32 is a lamp radiating a beam of visible light as its radiation 34. The radiation 34 impacts a reflector 36 or other radiation concentrating and directing means and is directed vertically downward through the sample OMPI _ well 18. A radiation sensor 38, such as a photocell, is situated directly beneath the flat bottom panel 20. The sensor 38 thus will detect any radiation 34 coming through the flat bottom panel 20 but will not detect radiation which does not pass thorugh panel 20. The sensor 38 then sends a signal to signal processing equipment 40 which is programmed to analyze the radiation trans- mittal characteristics of the contents of the given well 18. It may be seen that the construction of well 18 in the truncated conical segment 24 is such that radiation impinging upon the well wall 26 surrounding the flat bottom panel 20 is diffracted outward such that it does not impinge upon sensor 38 and does not contribute to the signal. It may also be seen that the presence of a precipitate or other opaque deposit 30 upon flat bottom panel 20 will prevent the transmittal of radiation to sensor 38 and will thus result in a null signal to signal processing equipment 40. In this mannmer the instrument can sense the presence or absence of the opaque deposit 30. In the preferred embodiment, the improved biomedical analysis tray 10 is constructed of virgin polystyrene. Any other material such as aerylonitrile which is transparent to the analysis radiation utilized by the instrument may be used as well provided it is resistant to breakdown from the chemicals utilized in the reactions. It is also possible to construct tray 10 to be opaque except at flat bottom panel 20. The dimensions of the tray 10 of the preferred embodiment are 13.647 em x 10.599 em (5.373" x 4.173") at the base, with a height of 1.476 em (0.581"). The planar upper plate 12 has lateral dimensions of 13.249 cm x 10.201 cm (5.216" x 4.016"). The ninety-six apertures and sample wells are arrayed in eight rows and twelve columns. The radius of each aperture is 0.337 cm (0.133"). Each well has a total depth of 1.148 em (0.452") to the upper interior surface of flat bottom panel 20. The right cylindrical segment has a depth of 1.041 cm (0.410") and the well walls have a thickness of 0.127 cm (0.050"). The thickness of flat bottom panel 20 is 0.152 cm (0.060") and the radius of the flat bottom panel 20 is also 0.152 cm (0.060"). The well wall 26 in the truncated conical segment 24 is inclined at an angle of 30° from horizontal. For ease of manufacture, the well wall 26 in the cylindrical segment 22 is tapered inward at an angle of 2° from aperture 16 to conical segment 24. This tapering allows tray 10 to be easily removed from the mold. The dimensions of the tray 10 and its components may be selected to match the desired processing instrument. Tolerances are dependent on manu- facturing and utilization conditions. In the preferred embodiment each of the ninety-six sample wells 16 is labeled such that the tray 10 is readily utilizable by laboratory technicians. The tray 10 is also specifically directed for use with the auto SCAN - 3 automated antibiotic suseptability/organism identification system of Micro-Scan, Inc. Although the present invention has been described above in terms of the presently preferred embodiment, it is to be understood that such disclosure is not to be considered as limiting. Accordingly, it is intended that the appended claims be interpreted as covering all alterations and modifications as fall within the true spirit and scope of the invention.

Claims: IN THE CLAIMS 1. An improved biomedical analysis tray comprising: a planar upper plate; a plurality of apertures arrayed through the planar upper plate; and a plurality of wells respectively depending from the edges of the apertures, each well including a flat bottom panel, transparent to analysis radiation, situated parallel to and below the aperture and of smaller area than the aperture, each well further including wall means extending from said edges of the aperture to said flat bottom panel. 2. A tray according to claim 1 and further including, support means for supporting the upper plate such that the wells are freely suspended when the tray is supported by the support means. 3. A tray according to claim 1 wherein, the apertures are circular. 4. A tray according to claim 3 wherein , said wall means include a right cylindrical segment adjacent to the aperture and a truncated conical segment extending between said right cylindrical segment and said flat bottom panel. 5. A tray according to claim 4 wherein, said flat bottom panel has a circular upper surface. 6. A tray according to claim 1 wherein, the tray is constructed of molded polystyrene. 7. In a tray for analysis of multiple solution samples including a plurality of sample-containing wells, the improvement comprising: a truncated conical segment at the bottom of each well, culminating in a flat bottom panel of smaller radius than the top radius of the well. 8. The improvement of claim 7 wherein, the ratio of the said top radius of the well to said flat bottom panel radius is approximately 4.43 to 1.

Inventors: RIEDEL CHRIS C, RIEDEL, CHRIS, C.
Applicants: AMERICAN MICRO SCAN INC, AMERICAN MICRO SCAN, INC.
Application year: 1982
Main classification: C12M1
IPC codes: B01L3, C12M1, G01N21