Abstract:
In a preferred embodiment, a combination stacker/incubator for microplates, including: a housing; an escapement mechanism disposed at a lower end of the housing to feed the microplates to and from the housing, such that the combination stacker/incubator serves as a stacker for more than one active microplate instrument; and heating apparatus disposed in the housing, such that the combination stacker/incubator serves as an incubator for the microplates.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of Provisional No. 60/101,104 filed Sep. 19, 1998 and is a continuation-in-part of co-pending U.S., patent application Ser. No. 09/198,018, filed Nov. 23, 1998, and titled ULTRA HIGH THROUGHPUT BIOASSAY SCREENING SYSTEM, the disclosure of which application is incorporated by reference hereinto. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to bioassay incubators generally and, more particularly, but not by way of limitation, to a novel combination stacker/incubator system for bioassay trays. 
     2. Background Art 
     In pharmaceutical research, there is an ongoing requirement to screen more compounds for bioactivity against a variety of therapeutic targets. This is accomplished with various bioassay methods. Currently, the standard format in which to conduct bioassays is a microplate measuring approximately 3×5 inches having wells in an 8×12 matrix on 9 mm centers. The trend is to higher density systems using the same 3×5 dimension, but with 384 wells in a 16×24 matrix on 4.5 spacing. 
     To process the various bioassays, there is a variety of instrumentation available, such as multiple pipettors, 96-and 384-well plate readers, and plate washers. To provide the automation desired, many of these instruments are supplied with plate stackers. The stackers serve as infeed and outfeed devices to the active instrument. 
     Many bioassays require an incubation period, at elevated temperatures—typically 37 degrees Centigrade. This follows the steps of pipetting reagents into the microplate which starts the reaction. Following this initial incubation period, additional steps of plate washing or reagent addition may be required. These additional reagent additions may be followed by another, or additional, incubation period(s) at elevated temperatures. 
     Each incubation step requires that the microplates be transported to an incubator device, the transport usually being provided by various shuttle table mechanisms, robotic arms, conveyors, etc. The microplates may pass through an intermediate step of being placed in the stacker before being moved to the incubator. After the incubation period, the microplates are again moved to the stacker from which they are fed to the primary instrument. 
     Such multiple handling of the microplates represents time that could be employed in additional bioassay procedures. 
     Accordingly, it is a principal object of the present invention to provide means and method to simplify the handling of microplates and the incubation process. 
     It is a further object of the present invention to provide such means and method that include heating the stacker such that the stacker serves as an incubator. 
     It is an additional object of the invention to provide such means and method that are economically achieved and used. 
     Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures. 
     SUMMARY OF THE INVENTION 
     The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a combination stacker/incubator for microplates, comprising: a housing; an escapement mechanism disposed at a lower end of said first housing to feed said microplates to and from said first housing, such that said combination stacker/incubator serves as a stacker for at least one active microplate instrument; and heating means disposed in said first housing, such that said combination stacker/incubator serves as an incubator for said microplates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Understanding of the present invention and the various aspects thereof will be facilitated by reference to the accompanying drawing figures, submitted for purposes of illustration only and not intended to define the scope of the invention, on which: 
     FIG. 1 is a partially schematic and partially exploded isometric view of a bioassay system, including a combination stacker/incubator according to the present invention. 
     FIG. 2 is a top plan view, in cross-section, of the combination stacker/incubator. 
     FIG. 3 is a schematic, partially cut-away, side elevational view of the combination stacker/incubator according to a variation of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference should now be made to the drawing figures, on which similar or identical elements are given consistent identifying numerals throughout the various figures thereof, and on which parenthetical references to figure numbers direct the reader to the view(s) on which the element(s) being described is (are) best seen, although the element(s) may be seen also on other views. 
     FIG. 1 illustrates a bioassay system, generally indicated by the reference numeral  10 , including a combination stacker/incubator according to the present invention, the latter being generally indicated by the reference numeral  20  and including a removable cover  22 . Combination stacker/incubator  20  is mounted on a base member  24 . 
     A stacker is basically a rectangular column or housing  30  that holds a plurality of microplates, as at  32 , in an orderly fashion and guides and aligns these plates, in a conventional manner, to a conventional escapement mechanism  34  disposed at the lower end of the housing. Escapement mechanism  34  is operated by an active device  40  that the stacker is serving. Active device may be, for example, a reader or a pipettor that transfers samples and/or reagents to or from microplate  32 , aspirates samples from the microplate, and/or washes the wells of the microplate. The exact type of device is not part of the present invention. 
     Escapement mechanism  34  may be a one-way device—that is, it serves to infeed microplates to active device  40 —or it may be a two-way device that both infeeds and outfeeds microplates  32 . In the present case, escapement mechanism  34  is a two-way device, since it is required to both put microplates  32  into combination stacker/incubator  20  or take them out of the combination stacker/incubator. There are many different possible arrangements for the stacker portion of combination stacker/incubator  20  and, in particular, for escapement mechanism  34 . These arrangements are primarily a function of active device  40  the stacker is to serve and the particular arrangement employed is not part of the present invention. 
     Represented by broken line  44  on FIG. 1, but not otherwise shown on the drawing figures of the present application, is a transport mechanism to move microplates  32  between active device  40  and combination stacker/incubator  20 . This transport mechanism may take the form of shuttle table mechanisms, such as the X-Y shuttle table shown in the above-referenced co-pending patent application, robotic arms, conveyors, etc. The exact mechanism employed is not part of the present invention, as the invention may be used with any of a number of different transport mechanisms. 
     In use, at least one additional stacker or combination stacker/incubator (not shown) is included to feed microplates  32  one-by-one to active device  40  where a processing step takes place. Microplates  32  are then transported one-by-one to combination stacker/incubator  20  for processing at an elevated temperature and are then transported one-by-one to active device  40  or to another active device. When a further processing step is completed at that active device, microplates  32  are transported one-by-one to the same, or to another, additional stacker or combination stacker/incubator. 
     Referring now primarily to FIG. 2, structural support for combination stacker/incubator  20  is provided by four, vertical, extruded, corner angles  50 , each having two integral guide portions  52  that position and align stacked microplates  32 . The exterior of combination stacker/incubator  20  is closed by four, vertical, smoke-grey, acrylic, outer panels  60  fixedly attached to corner angles  50 . Captured between panels  60  and corner angles  50  are four, vertical, aluminum, inner panels  70  captured between outer panels  60  and corner angles  50 . Each inner panel  70  has a vertical, inwardly bent, middle section  80  formed therein. Four, vertical, strip heaters  90  are fixedly attached to middle sections  80  in spaces  92  defined between the middle sections and outer panels  60 . Spaces  92  provide a form of temperature insulation via dead air space. Strip heaters  90  may be commercially available silicon or rubber strip heaters. A commercially available module  100  (FIG. 1) connected to strip heaters  90  provides proportional, derivative, and integral temperature control, in addition to having a temperature readout. 
     Strip heaters  90  (FIG. 2) provide temperature uniformity throughout combination stacker/incubator  20 , with inner panels  70  serving as heatsinks to uniformly distribute the heat from the strip heaters. A thermocouple  110  attached to one inner panel  70  provides temperature feedback to temperature module. If necessary to provide the desired degree of temperature uniformity in combination stacker/incubator  20 , strip heaters  90  may be wound with extra turns of wire at the lower ends thereof to increase the rate of heat transfer in the lower ends. 
     Combination stacker/incubator  20  is also designed as a removable cassette to enable the user to use the combination stacker/incubator as a transport carrier between compatible devices such as a pipettor and a reader. To make combination stacker/incubator  20  removable from base member  24 , four sliding type electrical contacts, as at  120  (FIG.  1 ), are provided to connect strip heaters  90  and thermocouple  110  (FIG. 2) to module  100 . Combination stacker/incubator  20  may thus be simply removed from base member  24  and plugged into a separate, compatible control unit mounted on another device. 
     FIG. 3 illustrates a further feature for providing uniform temperature throughout combination stacker/incubator  20 . Here, combination stacker/incubator  20  is disposed in a vertical housing  150  such that an air space  152  is defined between the inner surfaces of the walls of the housing and the outer surfaces of the walls of the combination stacker/incubator  20 . To assist in maintaining a uniform temperature of combination stacker/incubator  20 , a fan  160 , powered by motor  162 , disposed at the upper end of housing  150  is provided to force air downwardly around the combination stacker/incubator. A return duct  170  connecting the lower and upper ends of housing  150  provides for the recirculation of the air to fan  160 . Insulation (not shown) may be provided on the external surface of housing  150 , if desired. 
     The present invention thus extends the value of stackers in bioassay automation. The net result is that an automated pipettor with plate stackers can become a fully integrated bioassay workstation. System throughput is increased. The instrument also increases in value, since it can accomplish a wider range of tasks in the same space. 
     In the embodiments of the present invention described above, it will be recognized that individual elements and/or features thereof are not necessarily limited to a particular embodiment but, where applicable, are interchangeable and can be used in any selected embodiment even though such may not be specifically shown. 
     Terms such as “upper”, “lower”, “inner”, “outer”, “inwardly”, “outwardly”, and the like, when used herein, refer to the positions of the respective elements shown on the accompanying drawing figures and the present invention is not necessarily limited to such positions. 
     It will thus be seen that the objects set forth above, among those elucidated in, or made apparent from, the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown on the accompanying drawing figures shall be interpreted as illustrative only and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.