Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
1999-11-02
2003-01-07
Kim, John (Department: 1723)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C422S091000, C422S105000, C422S105000
Reexamination Certificate
active
06503456
ABSTRACT:
DESCRIPTION
The invention relates to a microplate with a particularly high packing density with a transparent base and to a process for its production.
Microplates, which are used for fluorescence, luminescence or scintillation measurements, for example in biochemical or molecular-biology questions, are known.
More recent luminescence and fluorescence techniques require the provision of dyed microplates with a transparent base. Microplates with ninety-six depressions currently constitute a standardized platform for the automatic or manual determination and evaluation of patient samples in widespread analyzers. A current method for the production of dyed microplates with a transparent base is the ultrasonic welding of a dyed plate frame to a transparent base. Both parts are preferably produced from polystyrene. However, the problem which occurs again and again is the absolute sealing of the ninety-six depressions with respect to one another. Double welded ribs are therefore often applied in order to achieve greater reliability.
EP 0 571 661 A1 discloses a microplate which can be used in measurement techniques in which light emission or translucency are determined. The microplate disclosed comprises an upper, opaque frame part forming a cell and a translucent base part, which has been welded to the upper frame part by means of ultrasound. Also known are variants of these microplates in which a protective grid produced from non-transparent material is fitted underneath the transparent base part and leaves optical windows free. It is also known to produce microplates of this type in the multi-component injection molding process, the frame and base parts being produced by means of two injection moldings and joined together.
In the case of the known microplates, it has proven to be disadvantageous that the transparent base parts, because of their thickness of about 1 mm, exhibit light conduction effects which are based on the refraction of light and on total reflection. Total reflection always occurs when light from an optically more dense medium falls onto the interface with an optically less dense medium, and the material-specific limiting angle is exceeded. This property is effectively used nowadays in light-conduction technology. Light is fed into the light conductor at one end, passes through it, because of total reflection, and can emerge again at the other end virtually unattenuated. However, the walls of the fibers must be absolutely smooth in optical dimensions for this purpose. If this is not the case, as in injection-molded parts, then the light is only partially totally reflected at each reflection, and can therefore emerge into adjacent depressions or cells. The undesired light-conduction effect also occurs, for example, in light transmission measurements, and therefore manifests itself, inter alia, in the fact that the transparent base acts as a light conductor and partially deflects light beamed into a specific cell into adjacent cells. In this connection, it has been established that as the thickness of the base increases, the light-conduction effect also increases, that is to say the measurement accuracy decreases. In addition, the known microplates, likewise because of the thickness of their transparent bases, are only conditionally suitable for radioactivity measurements, for example scintillation measurements.
The technical problem on which the present invention is based is therefore to provide microplates which overcome the above-mentioned disadvantages, in particular at the highest possible packing density, that is to say the highest possible number of depressions per microplate, which ensure a higher accuracy in the case of the optical measurements and, in addition, are also suitable for radioactive determinations.
The invention solves this problem by providing a microplate having the features of the main claim, in particular by providing a microplate having at least one frame part and at least one base part assigned to the frame part, the at least one frame part comprising a large number of cells, in particular at least 384 cells, and the at least one base part forming the bases of the cells, and the base part or, respectively, the bases of the cells having a thickness of at most 500 &mgr;m, preferably 20-500 &mgr;m, particularly preferably 40 to 100 &mgr;m.
In conjunction with the present invention, the frame part of a microplate is understood to be the part of a microplate which forms the cells or depressions, open toward the top and the bottom, in particular their side walls. The base part of a microplate is understood to be the part of a microplate which seals off the cells and, if appropriate, the cell interspaces at the bottom.
In conjunction with the present invention, a cell is understood to mean a vessel produced from any desired material, preferably plastic, which can be designed as a little bowl, depression, hole, hollow or the like and is used to hold samples to be examined.
In a particularly preferred way, the whole of the base part or only those parts of the base part which form the bases of the cells are designed as a membrane or as a film, especially a transparent film. In conjunction with the present invention, a film is understood to be a thin, preferably flexible, material layer which has no apertures, holes or the like and is accordingly impermeable to air and liquids. A film therefore has no filter function.
The invention therefore advantageously provides a microplate which, on account of the only very low thickness of the base part or, respectively, of the bases of the cells, makes a large number of advantages and applications possible. Because of the low thickness of the base part or, respectively, of the bases of the individual cells, it is for example particularly advantageously possible to carry out radioactivity determinations. If the base part is designed as a transparent film, the resultant advantage is that the undesired light-conduction effect is reduced considerably, so that the measurements can be carried out with an accuracy which is increased considerably by comparison with the prior art. If the base part is designed as a membrane, any possibly desired nutrient diffusion from below through the membrane into the (biological) cells growing on the membrane in the cell can take place particularly efficiently and largely unimpeded.
The microplates according to the invention are therefore suitable for any type of fluorescence, luminescence, colorimetric, chemiluminescence or radioactivity measurements, for example scintillation measurements. The microplates according to the invention can be used in ELISA tests, DNA and RNA hybridizations, antibody titer determinations, protein, peptide, immunological tests, PCR and cells. In particular, provision is made for the microplate according to the invention having standard dimensions (SBS standard dimensions, cf. description relating to
FIG. 1
) to have at least 384 cells. Of course, numbers of cells above or below this per microplate are also possible. For each frame part, it is therefore possible, for example, for there to be multiples of six, twelve, twenty-four, forty-eight or ninety-six cells, for example in a particularly advantageous embodiment 384, 768, 864, 1536 or 6144 cells.
The frame part is fitted to the base part, at most 500 &mgr;m thick, in the injection molding process, and thus closes the cells from below and at the same time provides the base for each individual cell. The microplate according to the invention may, for example, comprise such a frame part and a base part assigned to this frame part. According to the invention, however, provision may also be made to arrange one or preferably a number of frame parts removably in a base frame which is open at the center. A microplate of this type accordingly comprises a base frame and frame parts which are arranged in the base frame and are each provided with a base part.
In a further preferred embodiment, the invention provides for the frame part to be dyed white or black or else to be designed to be transparent or natura
Greiner Bio-One GmbH
Kim John
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