Growth container

Abstract: A petri dish 10 generally comprising a dish portion 12 covered by a lid portion 14. The dish portion 12 has a surface 16 and a peripheral dish wall 18 around the surface 16. The lid portion 14 has a ceiling plate 20 and a peripheral lid wall 22 around the ceiling plate 20. The lid wall 22 has a complementary shape with respect to the dish wall 18 to retain the lid portion 14 on the dish portion 12 in a number of predetermined positions. The petri dish 10 has a selector or selection features that are used to orient and place the lid portion 14 on the dish portion 12 in one of the positions to either restrict or permit a desired gas flow between the dish portion 12 and the lid portion 14. These features include a key 24 and a keyway 26 and a plurality of notched areas 28. The lid portion 14 is oriented with respect to and placed on the dish portion 12 to restrict gas flow when the key 24 fits within the keyway 26. The lid portion 14 is oriented with respect to and placed on the dish portion 12 to permit gas flow when the key 24 is not aligned with the keyway 26 and rests on the top edge 30 of the dish wall 18. The notched areas 28 are formed on one of the walls 22 and contact the other wall 18 when the lid portion 14 is oriented with respect to and placed on the dish portion 12 to permit gas flow.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention. The present invention relates, generally, to growth containers such as petri dishes. More particularly, the invention relates to petri dishes having a lid that can be oriented and placed on a dish in a number of predetermined positions to either restrict or permit gas exchange between the interior and exterior of the petri dish. 2. Background Information. A petri dish is a small shallow dish of thin glass or plastic with a loose cover that is used to grow tissue cultures and microorganisms on a solid culture. Generally, the lid covers the dish to prevent or minimize contamination during the culturing process. However, there will not be adequate gas exchange if the lid is fully inserted over the dish. Gas exchange is important for the culturing processes, and is especially important for anaerobic culturing processes in which oxygen-containing gas is removed or replaced from the petri dish. Typically, the lid is either completely removed or is only partially inserted over the dish when it is desired to expose the culture to ambient gas. It can be difficult to retain the desired position of a lid partially inserted on the dish when the petri dish is moved. Because large quantities of petri dishes may be used for some processes or experiments, the lid should be able to be quickly, effectively, and accurately placed, removed, and replaced on the dish. Additionally, it may be desirable to stack these petri dishes on top of each other because of space constraints. The state of the art includes various petri dishes. U.S. Patent No. 5,520,302 discloses a petri dish comprised of a generally rectangular dish and a lid. Two ' adjacent comers of both the dish and the lid are rounded and the other two adjacent corners of both the dish and the lid are notched. The lid has two positions on the dish. In a first position, the notched corners of the lid lie on the rounded comers of the dish and the rounded corners of the lid lie on the notched comers of the dish. The differently-shaped corners prevent the lid from being fully inserted over the dish in this position, allowing gas flow between the dish and the lid. In a second position, the notched corners of the lid are matched with the notched corners of the dish and the rounded corners of the lid are matched with the rounded corners of the dish. In this position, the lid is fully inserted over the dish and severely restricts or prevents gas flow between the lid and-the dish. U.S. Patent No. 4,675,298 discloses a petri dish that has projections formed on the periphery of the inner surface of the cover and has matching depressions on the rim of the lower dish. The projections and depressions provide an adjustable gap between the interior of the petri dish and the atmosphere. EP-A-0 171 174 discloses a Petri dish having abutments and positioning members located in confronting side walls of the base and the cover lid for locking the dish at different positions, wherein each position admits the entrance of ambient atmosphere into the dish at different rates. EP-A-0 119 984 discloses a Petri dish having position members located on the inner surface of the top wall of the cover lid and corresponding grooves located on an upper surface of the side wall of the base member, such as to allow entrance of ambient atmosphere into the dish when the position members and the grooves are mismatched. These Petri dishes allow a control of the rate of gas exchange with the outer environment depending on the relative position of the cover lid with respect to the base portion by means of a key/keyway mechanismus. US-A-3,597,326 discloses a stackable square-shaped multi-well Petri dish. The construction of this Petri dish does not allow to control the rate of gas exchange. Applicants' invention provides a petri dish which is believed to constitute an improvement over existing technology. BRIEF SUMMARY OF THE INVENTION The present invention provides an improved container or petri dish for growing tissue cultures and microorganisms. The petri dish generally comprises a base or dish portion covered by a lid portion. The dish portion has a surface and a peripheral dish wall around the surface. The lid portion has a ceiling plate and a peripheral lid wall around the ceiling plate. The lid wall has a complementary shape with respect to the dish wall to retain the lid portion on the dish portion in a number of predetermined or desired positions. The petri dish has a selector or selection features that an individual may use to quickly, effectively and accurately orient and place the lid portion on the dish portion in one of the desired positions to either restrict or permit a desired gas flow between the dish portion and the lid portion. These selection features may permit a desired gas flow in either a stackable or non-stackable configuration. These selection features include a key / keyway combination and a plurality of notched areas along the edge of one of the walls. The key is preferably a protrusion formed on the interior of the lid wall, and the keyway is preferably a small channel formed in the exterior of an upper wall portion of the dish wall. The lid portion is oriented with respect to and placed on the dish portion to restrict gas flow when the key fits within the keyway because the lid can be fully inserted over the dish. The key rests on the top edge of the dish wall when it is not aligned with the keyway so that the lid is only partially inserted over the dish to form a small vent opening that will permit a desired gas flow in a non-stackable configuration. The complementary shapes of the lid wall and dish wall retain the lid portion on the dish portion. The notched areas are formed along an edge of one of the walls and contact the edge of the other wall when the lid portion is oriented with respect to and placed on the dish portion to form uniformly spaced and larger vent openings. The lid portion and dish portion form these vent openings in a stackable configuration. These notched areas are preferably formed on the bottom edge of the lid wall. The notched areas have a predetermined vertical dimension and have a predetermined length to span across adjacent sides or segments of the dish wall when the lid portion is rotated with respect to the dish portion. The notches in the lid wall cooperate with the dish wall to retain the lid portion in the desired "rotated" position on the dish portion to permit a desired gas flow. The lid portion rests on the dish portion in a stable or secure manner, allowing other dishes to be stacked on top. The features, benefits and objects of this invention will become clear to those skilled in the art by reference to the following description, claims and drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING Figure 1 is a top plan view of the dish portion of the petri dish of the present invention. Figure 2 is a bottom plan view of the lid portion of the petri dish of the present invention. Figure 3 is a side view of the petri dish of the present invention, wherein the lid portion is oriented with respect to and is being placed on the dish portion in a predetermined position to restrict gas flow. Figure 4 is a side view of the petri dish of Figure 3, wherein the lid portion is placed on the dish portion in a predetermined position to restrict gas flow. Figure 5 is a side view of the petri dish of the present invention, wherein the lid portion is oriented with respect to and is being placed on the dish portion in a predetermined position to permit gas flow in a non-stackable configuration. Figure 6 is a side view of the petri dish of Figure 5, wherein the lid portion is placed on the dish portion and the key of the lid portion rests on the top edge of the dish wall in a non-stackable configuration. Figure 7 is a top plan view of the petri dish of the present invention in a predetermined position to permit gas flow in a stackable configuration, wherein the lid portion is rotated an offset amount and the notched areas of the lid portion span across adjacent dish walls. Figure 8 is a side plan view of the petri dish of Figure 7. DETAILED DESCRIPTION Referring to Figures 1-8, an example of the preferred embodiment of the present invention is illustrated and generally indicated by the reference numeral 10. The petri dish 10 is described below first in terms of its major structural elements and then in terms of its secondary structural and/or functional elements which cooperate to provide an economical petri dish that an individual can quickly, effectively, and accurately orient and place, remove, and replace a lid portion on a dish portion in a desired position to either restrict or permit a desired gas flow. The container or petri dish 10 generally comprises a base or dish portion 12 covered by a lid portion 14. The dish portion 12 has a surface 16 and a peripheral base or dish wall 18 around the surface 16, and the lid portion 14 has a ceiling plate 20 and a peripheral lid wall 22 around the ceiling plate 20. The lid wall 22 and the dish wall 18 have complementary shapes with respect to each other. The shapes of these walls 18 and 22 retain the lid portion 14 on the dish portion 12 in a number of predetermined positions to either restrict or permit a desired gas flow between the interior and exterior of the petri dish 10. The petri dish 10 has a selector or selection features that help an individual orient and place the lid portion 14 on the dish portion 12 in one of the desired positions to either restrict or permit a desired gas flow between the dish portion 12 and the lid portion 14. These features include a key 24 and a keyway 26 and a plurality of notched areas 28 in one of the walls. The petri dish 10 is preferably constructed or formed from a clear plastic. However, glass or other materials may be used. The surface 16 of the dish portion 12 is preferably a raised surface extending from the top edge 30 of the dish wall 18. The raised surface 16 may have a plurality of recessed wells 32 in which separate and distinct cultures may be grown within same petri dish 10. Preferably the dish wall 18 is an endless wall that extends around the periphery of the surface 16, and comprises a lower wall portion 34 and an upper wall portion 36. The lower wall portion 34 has a perimeter greater than the upper wall portion 36 and forms a lip 38 between the two wall portions. The lid wall 22 of the lid portion 14 is preferably an endless wall that extends down from the periphery of the ceiling plate 20. The bottom edge 40 of the lid wall 22 abuts against the lip 38 of the dish wall 18 when the lid portion 14 is fully inserted over the dish portion 12 to restrict gas flow. In a preferred embodiment shown in the figures, the petri dish 10 is about 7.62 cm (3 inches) long, 7.62 cm (3 inches) wide, and 1.27 cm (½ inch) high. The petri dish 10 has six recessed wells 32 positioned in a circular pattern in the dish portion 12. The wells 32 are approximately 1.27 cm (½ inch) deep and have a diameter of approximately 1.905 cm (¾ inch) The top surface of the top or ceiling plate 20 preferably has ridges 48 that cooperate with the dish wall 18 of a stacked petri dish 10. The ridges 48 promote proper alignment between the lid portions and dish portions of stacked petri dishes, and prevent a stacked petri dish from slipping of the lid of the bottom petri dish. The figures show the key 24 and keyway 26 formed in the lid portion 14 and the dish portion 12, respectively. The key 24 is preferably a small protrusion, 0.159 cm (1/16 inch) in the illustrated embodiment, formed on the interior of the lid wall 22, and the keyway 26 is preferably a small channel formed in the exterior of the dish wall 18 and sized to receive the key 24. However, the key 24 could be formed in the dish portion 12 and the keyway 26 could be formed in the lid portion 14. In a preferred embodiment shown in the figures, the lid portion 14 and dish portion 12 of the petri dish 10 have a generally square configuration or footprint that allow the lid portion 14 to fit over the dish portion 12 at four rotational positions (0°, 90°, 180°, and 270°) with respect to each other. The corners of the lid portion 14 and dish portion 12 are preferably rounded. Other symmetrical shapes that have adjacent sides, such as triangles or pentagons, would function similarly to the illustrated embodiment as described below. Referring to Figures 3-4, the lid portion 14 is ' oriented with respect to and placed on the dish portion 12 at 0°, for example, where the key 24 fits within the keyway 26. Gas flow is restricted in this position because the lid portion 14 can be fully inserted over the dish portion 12 where the bottom edge 40 of the lid wall 22 abuts against the lip 38 of the dish wall 18. The key 24 is not aligned with the keyway 26 when the lid portion 14 is oriented with respect to and placed on the dish portion 12 at 90°, 180°, or 270°. In these positions, as illustrated in Figures 5-6 , the key 24 rests on the top edge 30 of the dish wall 18. A relatively small vent opening 42 is formed to permit a desired gas flow. On the opposite side of the lid portion 14, the bottom edge 40 of the lid wall 22 abuts against the lip 38 of the dish wall 18. The remainder of the lid wall 22 retains the lid portion 14 on the dish portion 12 in the desired position because, as shown in Figures 3 and 6 , the bottom of the key 24 is higher than the bottom edge 40 of the lid wall 22. Multiple keys 24 and / or multiple keyways 26 may be used to provide additional positions where the lid portion 12 would be fully inserted over the dish portion 12 to restrict gas flow. The petri dishes are not stackable in this configuration. The notched areas 28 are formed on one of the walls and contact the other wall when the lid portion 14 is oriented with respect to and placed on the dish portion 12 to form uniformly spaced and larger vent openings 42 that will permit a desired gas flow. As illustrated in the bottom plan view of the lid wall 22 shown in Figure 2, the notched areas 12 are formed on the bottom edge 40 of the lid wall 22 and contact the top edge 30 of the dish wall 18 in a preferred embodiment. However, the notched areas 12 could be formed in the top edge 30 of the dish wall 18 and contact the bottom edge 40 of the lid wall 22, or both walls 18 and 22 could be formed with notched areas 12 on their respective edges. The notched areas 28 have a predetermined vertical dimension and, as shown in Figures 7-8 , have a predetermined length to span across adjacent sides or segments of the dish wall 18 when the lid portion 14 is rotated with respect to the dish portion 12. For the generally square petri dish 10 illustrated in the figures, the notched areas 28 in the lid wall 22 extend across adjacent sides or segments of the dish wall 18 when the lid portion 14 is oriented at about 45°, 135°, 225°, and 315° with respect to the dish portion. A notched area 28 is generally centered along each side of the lid wall 22, and each notch area has a length of approximately 1 1/8 inch in the illustrated embodiment. Other symmetrical shapes that have adjacent sides, such as a triangle, pentagon, etc., would function similar to the illustrated embodiment as described below. The lid wall 22 retains the lid portion 14 on the dish portion 12 in the desired "rotated" position to form vent openings 42 that will permit a desired gas flow. The positioning of the lid portion 14 illustrated in Figure 8 provides vent openings 42 that are uniformly spaced and are relatively larger than the vent openings formed by the positioning of the lid portion 14 illustrated in Figure 6 . The petri dishes are stackable in this configuration.

Claims: A petri-dish (10) comprising: (a) a base portion (12) having a bottom surface (16) and a peripheral wall (18) around said surface (16): (b) a lid portion (14) having a top plate (20) and a peripheral wall (22) around said top plate (20), said lid wall (22) having a complementary shape with respect to said base wall (18) to retain said lid portion (14) on said base portion (12) in a plurality of predetermined positions; and (c) a selector for orientating and placing said lid portion (14) on said base portion (12) in one of said positions to either restrict or permit gas flow between said base portion (12) and said lid portion (14), characterised in that the selector comprises a keyway (26) in the peripheral wall (18) of the base portion (12), a plurality of notched areas (28) formed in the peripheral wall (22) of the lid portion (14) for permitting gas flow between said base portion (12) and said lid portion (14) when said lid portion (14) is orientated with respect to and placed on said base portion (12) in a first position and a key (24) formed by said lid wall (22) for fitting within the keyway (26) when the lid portion (14) is orientated with respect to and placed on said base portion (12) in a second position to restrict gas flow. The petri-dish of claim 1, wherein said base wall (18) includes a lower wall (34) separated from an upper wall (36) by a lip (38), said lower wall (34) having a perimeter greater than said upper wall (36) and approximately equal to said lid wall (22), said lid wall (22) extending around said upper wall (36) and abutting against said lip (38) when said lid portion (14) covers said base portion (12) to restrict gas flow between said base portion (12) and said lid portion (14). The petri-dish of claim 1 or claim 2, wherein said key (24) is not aligned with said keyway (26) and rests on the top edge (30) of said peripheral wall (18) of the base portion (12) when said lid portion (14) is orientated with respect to and placed on said base portion (12) in at least one of said positions to permit gas flow. The petri-dish of claim 3, wherein said base portion (12) and said lid portion (14) are in a non-stackable configuration when said key (24) is not aligned with said keyway (26). The petri-dish according to any one of the preceding claims, wherein said bottom surface (16) is a raised planar surface extending from the top edge (30) of said base wall (18), said raised surface (16) containing the at least one recessed well (32). The petri-dish of any one of the preceding claims, wherein said notched areas (28) contact the top edge (30) of said base wall (18) when said lid portion (14) is orientated with respect to and placed on said base portion (12) in said first position to permit a desired gas flow. The petri-dish of claim 6, wherein said base wall (18) has sides and wherein said notched areas (28) have a predetermined vertical dimension compared to the remainder of said lid wall (22) and have a predetermined length to span across adjacent sides of said base wall (18) when said lid portion (14) is orientated with respect to and placed on said base portion (12) to permit a desired gas flow. The petri-dish of claim 6 or claim 7, wherein said lid wall (22) and said base wall (18) have a generally square configuration comprised of four sides, said lid wall (22) having four notched areas (28), each of said notched areas (28) being generally centred along one of said sides of said lid wall (22). The petri-dish of any one of the preceding claims, wherein said base portion (12) and said lid portion (14) are in a stackable configuration when said notched areas (28) contact the peripheral wall (18) of the base portion (12). The petri-dish according to any one of the preceding claims, wherein said top plate (20) has a top surface with ridges (48) positioned and arranged to cooperate with said peripheral wall (18) of said base portion (12) of a stacked container, said ridges (48) preventing said stacked container from slipping. A petri-dish (10) comprising: (a) a base portion (12) having a surface (16) and a peripheral base wall (18) around said surface (16), (i) said base wall (18) including a lower wall (34) separated from an upper wall (36) by a lip (38), said lower wall (34) having a perimeter greater than said upper wall (36) and approximately equal to said lid wall (22), said lid wall (22) extending around said upper wall (36) and abutting against said lip (38) when said lid portion (14) is orientated with respect to and placed on said base portion (12) to restrict gas flow between said base portion (12) and said lid portion (14), (ii) said base wall (18) having a keyway notch (26) orientated outward from said base wall (18), and (iii) said surface (16) being a raised planar surface extending from a top edge (30) of said base wall (18), said raised surface (16) containing at least one recessed well (32); and (b) a lid portion (14) having a ceiling plate (20) and a peripheral lid wall (22) around said ceiling plate (20), said lid wall (22) having a complementary shape with respect to said base wall (18) to retain said lid portion (14) on said base portion (12) in a number of predetermined positions, (i) both said lid wall (22) and base wall (18) having a generally square configuration comprised of four sides, (ii) said lid wall (22) having a notched area (28) on each side of said lid wall (22), each of said notched areas (28) having a shorter predetermined vertical dimension compared to the remainder of said lid wall (22), each of said notched areas (28) being generally centred along one of said sides of said lid wall (22), said notched areas (28) of said lid (14) resting on a top edge (30) of said base wall (18) when said lid (14) is orientated with respect to and placed on said base portion (12) in one of said positions to permit gas flow, each of said notched areas (28) having a predetermined length and spanning across adjacent sides of said base wall (18) when said lid portion (14) is orientated with respect to and placed on said base portion (12) in one of said positions to permit gas flow, (iii) said lid wall (22) having a key (24) formed in said lid portion (14), said key (24) being received by said keyway notch (26) when said lid portion (14) is orientated with respect to and placed on said base portion (12) in one of said positions to restrict gas flow, said key (24) resting on a top edge (30) of said base wall (18) when said lid portion (14) is orientated with respect to and placed on said base portion (12) in one of said positions to permit gas flow, and (iv) said ceiling plate (20) having a top surface with ridges (48) positioned and arranged to cooperate with said base wall (18) of said base portion (12) for a stacked container, said ridges (48) preventing said stacked container from slipping.

Inventors: ANDERSON MARK L, HARMON JOHN C, ANDERSON, MARK L., HARMON, JOHN C.
Applicants: ANDERSON MARK L, ANDERSON, MARK L.
Application year: 2000
Main classification: C12M1
IPC codes: C12M1