Optics: measuring and testing – Sample – specimen – or standard holder or support
Reexamination Certificate
1998-06-17
2001-06-19
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Sample, specimen, or standard holder or support
C356S246000
Reexamination Certificate
active
06249344
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for sedimentation and optical examination of particles suspended in a fluid, further a cuvette to accomplish said method.
BACKGROUND OF THE INVENTION
In laboratory practice the necessity of optical., microscopic examination of particles suspended in a fluid (emulsion or suspension) often arises to classify the particles according to their shape and determine concentrations of various fractions. In medical practice, determination of blood cell counts or analysis of urine sediments may constitute such tasks. Several similar examinations are carried out in other fields of industry, e.g. in food processing or pharmaceutical industry.
Such examinations are conventionally performed by filling the sample into a test tube, sedimentation it by centrifuging for a required period, removing the supernatant, homogenizing and staining the sediment if required, and transferring a drop of it to a microscope slide, covering it with a coverslip and evaluating the observed image with human eye through a microscope, and repeating this evaluation on a required number of imaging areas.
The above traditional method is extraordinarily inaccurate, time-consuming and can hardly be automated. Numerous methods have been developed to simplify the conventional method.
According to a known method suitable for investigating particles suspended in a fluid, the sample of considerable volume is passed through a flow-cell and the particles flowing in the sample are optically observed and analysed. Such methods are described in Patent Specifications of No. U.S. Pat. Nos. 4,393,466 and 5,123,055.
Deficiency of the methods known so far is that the moving particles can be observed optically for a very short time only, therefore, owing to the limited time available for classifying each particle, practically there is no way to perform morphological testing.
DISCLOSURE OF THE INVENTION
The object of the invention is to provide an improved method lending itself to easy automation, beside being quick and relatively accurate.
Another object of the invention is to provide an apparatus suitable for preparing particles suspended in a fluid for optical examination.
A further aim of the invention is to develop a cuvette permitting quick preparation of particles suspended in a fluid for optical examination and to perform said optical examination by means of the said cuvette.
According to one aspect of the invention a method is provided for sedimentation and optically examining particles suspended in a fluid, in the course of which the sample to be tested is settled, and the sediment is examined optically. This method comprises the following steps: placing the sample stained as required into a cuvette provided with a planar
baseplate and sedimentation it therein, and after sedimentation optically examining the sample from below, with cuvette held
in horizontal position.
According to a preferred embodiment of the invented method the sedimentation of sample is carried out by centrifuging. Further, it is preferred that the ratio between the component of acceleration perpendicular to baseplate and the component parallel to the latter and acting on said cuvette be maintained at a value higher than 10.
According to another aspect of the invention a device is provided for implementing the method. The invented apparatus comprises a conveyor and a cuvette dosing device arranged along said conveyor, further a moving mechanism forwarding the cuvettes along the conveyor and a sample feeder, wherein the cuvettes are provided with a planar baseplate. Along the conveyor a centrifuge is arranged which is followed by an optical unit consisting of a microscope objective and a horizontally positioned object platform having an opening therein. Said microscope objective placed under said object platform.
In a preferred embodiment of the device said centrifuge is provided with a self-aligning cuvette holder mounted to an arm. The centrifuge can be fitted with a vertical shaft to which the cuvette holder is coupled through a pivotal joint permitting rotation in two degrees of freedom.
In a further preferred version the centrifuge is fitted with a horizontal shaft. Said cuvette holder is mounted onto the shaft through either a fixed or a pivoting joint permitting rotation around an axis parallel with the horizontal shaft, if said joint is of a fixed type it is to fix said cuvette holder in a fixed position with respect to said shaft. This fixed position is both parallel with the axis of the shaft and horizontal while the shaft is in its end position after finishing centrifugation. This is the lowermost position of the cuvette in the centrifuge and it is oriented horizontally for preventing tangential displacement of the sediment. The centrifuge should start preferably from the same angular position to keep the cuvette horizontal before centrifugation.
Said object platform and microscope objective of the optical unit are coupled to each other preferably by a sealing permitting axial displacement, said sealing confining a vacuum chamber between said microscope objective and said object platform. A vacuum pump is connected through a vacuum connecting pipe to said vacuum chamber. The suction provided by said vacuum pump presses the cuvette against said platform and thereby the distance of the cuvette baseplate to the microscope objective can be kept constant.
According to a further aspect of the invention a cuvette is provided for implementing of the above method and for being used in conjunction with the apparatus described above. Said cuvette is provided with a planar baseplate and a coverplate is attached to said baseplate, through a frame of uniform thickness. Said cuvette is further provided with an opening for filling the sample into the interior of said cuvette. Said baseplate of said cuvette is resilient to a measure enabling its resilient deformation to fit closely to the periphery of said opening provided in the object platform of said optical unit.
In a preferred embodiment of said cuvette said opening for filling in the sample is leading through the frame and is in fluid communication with the space confined by baseplate and coverplate. Said opening is fitted with a plug for shutting off the opening.
REFERENCES:
patent: 3141547 (1964-07-01), Newby
patent: 3873021 (1975-03-01), Paulsen
patent: 4452902 (1984-06-01), Suovaniemi et al.
patent: 4595563 (1986-06-01), Degrave
patent: 4609991 (1986-09-01), Minton et al.
patent: 4895453 (1990-01-01), Devlin et al.
patent: 0628824A1 (1994-12-01), None
Font Frank G.
Nguyen Tu T.
Nikaido Marmelstein Murray & Oram, LLP.
Roche Diagnostics GmbH
LandOfFree
Method and apparatus for sedimentation and optical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for sedimentation and optical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for sedimentation and optical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2530097