Chemistry: analytical and immunological testing – Optical result – Including reagent preparation
Reexamination Certificate
2000-03-31
2003-04-08
Alexander, Lyle A. (Department: 1743)
Chemistry: analytical and immunological testing
Optical result
Including reagent preparation
C436S808000, C422S051000, C422S067000, C427S258000, C427S286000, C427S338000, C427S414000
Reexamination Certificate
active
06544796
ABSTRACT:
The present invention concerns a system for producing multiple diagnostic test elements comprising,
a support with an analytical region for applying diagnostic test spots and one or several stop edges for each direction in space to position the support,
a first holding unit into which the support is inserted and positioned by means of one or several stop edges,
a first printing head which is arranged above the holding unit and which is used to release fluid drops of a first liquid onto the analytical region of the support,
a first positioning unit which laterally displaces and positions the first holding unit,
a second holding unit into which the support is inserted and positioned by means of one or several stop edges,
a second printing head which is arranged above the second holding unit and is used to release fluid drops of a second liquid onto the analytical region of the support,
a second positioning unit which laterally displaces and positions the second holding unit,
a transport unit which transports the support into the holding units,
a control unit which controls the transport unit, the holding units and the positioning units and the release of liquid from the printing heads.
The present invention additionally concerns multiple diagnostic test elements in which a plurality of test spots are arranged particularly exactly in a predetermined pattern and also a production process for such test elements and an analytical method using multiple test elements.
Test elements have already been known for some time in the prior art in which various reagents are applied to a support. For example an indicator is described in the German Patent DE 27 27 347 in which two or several substances are applied to zones on the support surface on a support which have a certain spacing. Printing techniques such as screen printing or electrostatic printing and the so-called ink-jet printing are disclosed for applying the reagents to the surface. A process for the production of reagent supports is also described in U.S. Pat. No. 4,216,245 in which two or several reagents are applied in non-overlapping regions of the surface. In the aforementioned documents this procedure is chosen to avoid undesired interactions of the reagents. In contrast test elements are described in the U.S. Pat. Nos. 5,378,638 and 4,591,570 that are suitable for immunological tests. A method is described in U.S. Pat. No. 4,591,570 in which various solutions of antibodies are applied manually to the support using a pipette. The diameter of the surface regions (spots) is between 0.25 and 1 mm. An apparatus for the automatic production of supports containing a plurality of small test spots is described in U.S. Pat. No. 5,338,688. The support to be coated is located on a positioning table which can be moved laterally and a single printing head for applying drops of liquid is located above the support. In this document it is pointed out that it is possible to generate patterns of various types of liquid which are arranged alternately. However, it is not shown how such a pattern can be generated in practice.
The object of the present invention was to propose a device and a process for the production of multiple test elements which produces test elements that have particularly small test zones in a highly accurate predetermined arrangement. In particular an object of the present invention was to provide such precise test elements in which the test spots have different compositions. An additional object of the present invention was to propose a device for producing test elements and a suitable process that can be used to reliably and rapidly produce the test elements according to the invention.
The present invention has achieved the said objects by providing a system as claimed in claim 1. This system can be used to produce multiple test elements which have a very accurate pattern of small test zones.
Multiple test elements which can be produced with a production system of the present invention have a support on which an analytical region is located. A plurality of essentially circular test spots is applied in the analytical region in a specified pattern. The diameter of the individual test spots is preferably less than 350 &mgr;m and the centres of the test spots deviate by less than 40 &mgr;m from the specified pattern. Such an accurate arrangement of test spots is unknown in the prior art. Letters and such like can also be generated by a pattern of very accurately arranged individual spots when using ink-jet printing heads in conventional printers. However, a problem in the present invention is that the test zones of the multiple test elements cannot be applied with a single printing head and instead several printing heads filled with different printing liquids are required. Colour printers are known in the prior art in which different liquids are applied using several printing heads or one printing head with several chambers. In such colour printers the paper and the printing heads are moved. Such an arrangement is less suitable for the production of very precise test elements since neither the absolute nor the relative accuracies of the positioning are adequate. In addition colour printers of the prior art do not enable the high printing densities required for the present invention composed of different test spots that are separated from one another. It was found that the positioning inaccuracy is mainly due to the fact that the printing heads are moved during the printing process. Other disadvantages of colour printers are the use of a relative large distance between the discharge nozzle of the printing head and the printed material. The present invention discloses an improved method and system for producing exact test elements with different test spots which avoids the disadvantages of the prior art.
In the production of multiple test elements the manufacture already knows the desired pattern so that a deviation of the test spots from the pattern and the extent of the deviation can be simply determined by a microscopic evaluation or similar methods. The deviation from the pattern can, however, also be determined when the specified pattern is unknown since the patterns used in practice are strict geometric arrangements such as squares, rectangles, honeycombs etc. In the said patterns there are always rows of test spots. Hence, in order to determine deviations from the pattern, the centres of test spots that are located in a row can be joined together by a fitting line. The deviation from the pattern is given in a simple manner by the distance of the individual test spot centres from the line of fit. In this definition of distance it is assumed that different types of test spots are in the observed rows. It is technically relatively simple to achieve the inventive precision for rows of similar test spots which can be produced with one and the same printing head.
The analytical region of multiple test elements according to the invention is preferably planar and has an unevenness of less than 100 &mgr;m, particularly preferably of less than 10 &mgr;m. The analytical region is preferably made of a material into which the liquids cannot penetrate or only to a very slight extent. Suitable materials are in particular plastics of which polystyrene has proven to be particularly advantageous. However, the analytical region can also be composed of glasses, metals or silicon which have suitable surface properties. The analytical region onto which the test spots are applied is preferably hydrophobic in order to avoid bleeding of the printed liquid drops. The use of a hydrophobic surface for the analytical region, compatible printing liquids to generate test spots and suitable methods for applying test spots can ensure that the test spots have a defined size and shape.
The analytical region should also have a sufficiently homogeneous surface which has only a few defects and little unevenness. The defects on the surface should be so small that the longest dimension of the imperfection is less than 10 &mgr;m and the unevenness of the surfac
Eichenlaub Udo
Masch Martin
Alexander Lyle A.
Brinks Hofer Gilson & Lione
Roche Diagnostics GmbH
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