Field of the Invention The invention relates generally to the field of microplates and, more specifi- cally, to a machine for securing a lid to or removing a lid from a microplate.

Background Information Microplates are commonly used in a variety of test procedures. During such procedures, it may be desirable or necessary to cover or seal the wells contained in the microplates in order to produce appropriate test conditions, prevent cross- contamination among wells, prevent sample leakage during transportation or storage, or prevent human exposure to hazardous samples. In addition, some test procedures, in- cluding high throughput screening, may require a large number (e. g., on the order of hundreds or thousands) of microplates to be handled rapidly. In such an environment, it is essential that the process of engaging or disengaging the microplate's cover does not interfere with or unduly reduce the throughput of the system.

Conventional microplate covers suffer from several significant disadvantages.

First, most covers are not adapted to work with robotic or other automatic handling ma- chines, which effectively forces users to engage or disengage the covers by hand. Such manual handling is commercially unacceptable in applications such as high throughput screening. Second, manually engaging/disengaging the covers presents a safety hazard due to possible contact with hazardous samples or risk of injury from sharp-edged cov-

ers which typically require considerable force to engage or disengage. Third, repeated manual handling may also increase the risk of damage to either the microplate or cover.

SUMMARY OF THE INVENTION In brief summary, the present invention provides a machine for engaging a mi- croplate cover (lid) with or removing the cover from a microplate. The machine, sometimes referred to herein as a lidder/delidder, is simple to operate, requiring only the rotation of a hand crank to either engage or disengage a cover with a microplate.

In a preferred embodiment, the machine provides an enclosure having a hinged top and a latch for securing the top in a closed position. A hand crank extends from one side of the enclosure. When the latch is released and the top is open, access may be gained to an interior platform on which a microplate may be placed. If a cover is al- ready engaged with the microplate, the top of the enclosure is closed and latched. A user rotates the crank approximately 90° from its starting position. During the first part of the crank's rotation, a set of cams engage the sides of the cover. The cams flex or bow the sides of the cover such that they spread outwardly and clear the bottom edge of the microplate. Simultaneously, the platform on which the microplate rests is lowered and the microplate descends beneath the cover. At that point, the top of the enclosure may be opened, and the disengaged cover and microplate removed.

To engage a cover with a microplate, the microplate is placed on the platform and the cover is placed in a holder which suspends the cover above the microplate.

The top of the machine is closed and latched. The hand crank is rotated, again ap- proximately 90° from its starting position, but in the opposite direction from that used to disengage the cover. This action causes the set of cams to flex the cover's sides and spread the sides apart. As the crank continues to rotate, the platform rises and brings the microplate into contact with the cover. As the crank completes its rotation, the cams release the sides of the cover, thereby allowing the sides to return to their normal positions and engage the bottom edge of the microplate.

The present invention provides a rugged, reliable, and safe approach to engag- ing and disengaging microplate covers. Risk of injury to a user is practically elimi- nated as most of the action occurs inside the enclosure away from the operator's per-

son. The hand crank may be positioned on either side of the machine to accommodate either right or left-handed users. In addition, the direction in which the crank must be rotated to perform an engagement or disengagement may be selected by the user.

BRIEF DESCRIPTION OF THE DRAWINGS The invention description below refers to the accompanying drawings, of which: Fig. 1 is an exploded, perspective view of a microplate lid assembly; Fig. 2 is a perspective view of a machine, constructed in accordance with a pre- ferred embodiment of the present invention, for engaging the lid assembly of Fig. 1 with or disengaging same from a microplate; Fig. 3 is a perspective view of the machine of Fig. 2 in which the top is open; Fig. 4 is a perspective view of the machine of Fig. 2 with the enclosure panels removed to reveal the internal construction ; Fig. 5 is a perspective view of the machine of Fig. 4 showing the crank in a po- sition to begin a disengagement of a microplate cover; Fig. 6 is a perspective view of the machine of Fig. 4 showing the crank in a po- sition to being an engagement of a microplate cover; and Fig. 7 is an assembly drawing of the machine of Fig. 4 DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT Figure 1 shows a microplate cover assembly 2 which may be used to seal wells 6 contained in a microplate 4. Microplate 4 is of conventional design and is available from any of a number of commercial sources in any of 24,96 or 384 well formats, and may include others. It should be understood that the term"microplate"as used herein includes, but is not limited to, shallow well, deepwell, half deepwell and PCR type plates as well as minitube racks. It should also be understood that the present invention is not limited to any particular matrix size.

A cover 8 is disposed on a pressure plate 10. Pressure plate 10 is disposed on a layer of sealing material 12, which in turn is disposed on the top surface of microplate

4. Cover 8 includes an angled top surface 16 with a narrow, generally flat portion 18 extending laterally along the central axis of the cover. Cover 8 includes sides 14a and 14b which are generally orthogonal to top surface 16. Extending laterally from the edges of top surface 16 are tabs 20a-20d which function as gripping points for either the lidder/delidder described below or a robotic handling system (not shown).

Pressure plate 10 includes two tabs 1 la, 1 lb which are used to properly position cover assembly 2 prior to engaging the assembly with a microplate, as described in de- tail below.

Each side 14a, 14b includes a generally rectangular aperture, only one of which, 22b, is visible in this figure. Such apertures allow side surface 28 of microplate 4 to remain visible when assembly 2 is engaged with the microplate. Thus, identifying marks or bar code labels, which are often located on side surface 28, are not obscured once microplate 4 is sealed. In addition, such apertures increase the flexibility of sides 14a, 14b, thereby reducing the force necessary to either engage or disengage cover 8 from microplate 4.

Each side 14a, 14b also includes an inwardly-extending flange, only one of which, 24a, is partially visible. Such flanges extend laterally for most of the lengths of sides 14a, 14b and, when cover 8 is engaged with microplate 4, support a bottom edge 30 of microplate 4, keeping the microplate from distorting and anchoring the cover to the microplate.

The bottom corner of each side 14a, 14b also includes a foot, three of which, 26a-26c, are visible in this figure. Such feet allow multiple cover assembly 2/microplate 4 units to be stacked one upon another.

Cover 8 and pressure plate 10 are preferably constructed from stainless steel or conventional spring steels with corrosion resistant plating or coatings. Layer 12 is preferably constructed from a material sold under the trademark GEON. It will be ap- parent to those skilled in the art that a wide variety of other suitable materials may be substituted including Techron, EVA, Neoprene, polypropylene or Teflon@ films.

In a preferred embodiment, cover 8, pressure plate 10 and sealing layer 12 are joined together by a mechanical arrangement such as swaged over tabs, spot welding or

riveting. Pressure plate 10 and sealing layer 12 are preferably joined with a conven- tional adhesive such as cyano-acrylate or pressure sensitive adhesive suitable for the material being bonded. With its components fastened together, cover assembly 2 may be more easily engaged with and disengaged from microplate 4.

Figure 2 shows a lidder/delidder 32, constructed in accordance with a preferred embodiment of the present invention, which may be used to manually engage or disen- gage cover assembly 2 from microplate 4. A generally rectangular housing 34 has a hinged top 36 which is secured by a latch 38. A hand crank 40, shown in its neutral (vertical) position, is located on the right side of housing 34 and is connected to a shaft 46. Lidder/delidder 32 is preferably constructed primarily from stainless steel, but any of a number of other materials may be used.

As may be seen more clearly in Figures 3 and 4, when latch 38 is released, top 36 opens, thereby enabling a user to gain access to the interior of housing 34. Two re- cesses, 48a, 48b, are shaped and dimensioned to receive tabs 1 la, 1 lb (Fig. 1) of pres- sure plate 10. Thus, when a free (unengaged) cover assembly 2 is placed into lid- der/delidder 32, the assembly 2 will rest on recesses 48a, 48b.

A movable platform 42 is shaped and dimensioned to support a microplate (omitted for clarity), like microplate 4 (Fig. 1), to which a cover may or may not al- ready be engaged. Four cams, only two of which, 44a, 44b, are visible in this figure, are disposed proximate to each corner of platform 42, respectively. Platform 42 and cams 44 are mechanically coupled to hand crank 40.

With reference to Figures 1 and 4-6, the operation of lidder/delidder 32 will now be described. Let us assume that a user wishes to engage a cover with a micro- plate. As shown in Figure 6, when hand crank 40 has been rotated clockwise to its maximum position, platform 42 is lowered by several inches from its highest position.

This is the normal starting position for engaging a cover with a microplate. A cover assembly 2 is then placed above the microplate and supported in that position by tabs 1 la, 1 lb resting on recesses 48a, 48b, respectively. The user closes top 36, thereby en- gaging latch 38.

Next, the user rotates hand crank 40 in a counterclockwise direction (i. e., pull- ing the handle of the crank toward the user). As hand crank 40 rotates, it turns shaft 46 which causes several actions. First, cams 44 begin to rotate and cause the sides 14a, 14b of cover 8 to flex outwardly. As hand crank 40 continues to rotate, platform 42 begins to lift and eventually brings the top surface of microplate 4 in contact with seal- ing material 12. At that point, cams 44 begin to rotate in the opposite direction, slowly allowing sides 14a, 14b to return to their original positions. As sides 14a, 14b return to their original positions, flanges 24a and 24b move under the bottom surface 30 of mi- croplate 4, thus securing cover assembly 2 to the microplate.

Now, consider the example of disengaging a cover from a microplate. As shown in Figure 5, the hand crank 40 has been rotated counterclockwise to its maxi- mum position. This is the normal starting position for disengaging a cover from a mi- croplate. Platform 42 is at its maximum height. A microplate 4, with engaged cover assembly 2, is placed on platform 42. The user then closes top 36 of the lidder/delidder 32. As the user begins to rotate crank 40 in a clockwise direction (i. e., away from the user), cams 44 begin to rotate and force sides 14a, 14b of cover 8 to flex outwardly.

Platform 42 then begins to descend, causing microplate 4 to drop below and clear of cover 8. As crank 40 completes its clockwise rotation, cams 44 slowly release sides 14a, 14b, which return to their original positions.

As shown in Figure 7, an assembly drawing of lidder/delidder 32, hand crank 40 may be attached to either side of lidder/delidder 32 to accommodate either right or left- handed users. In addition, the actions induced by crank 40 may be reversed from those described above, such that the user may choose in which direction of crank rotation a cover engagement or disengagement procedure is carried out.

Those skilled in the art will recognize that while a preferred embodiment of the invention described above relies on a hand crank, other manually operated devices could be substituted for the crank. In addition, a motor or other drive could be used to partially or fully power the operation of the lidder/delidder.

What is claimed is: