Optics: measuring and testing – For light transmission or absorption – Of fluent material
Reexamination Certificate
1998-05-13
2001-05-29
Font, Frank G. (Department: 2877)
Optics: measuring and testing
For light transmission or absorption
Of fluent material
C356S440000, C356S246000
Reexamination Certificate
active
06239875
ABSTRACT:
The invention relates to a photometric measuring system, comprising a holder provided with at least one storage chamber for holding a fluid to be measured, at least one light generator for generating a light beam to interact with the fluid in the storage chamber and at least one light detector for detecting, during operation, at least a portion of the light which has interacted with the fluid present in the storage chamber, in which system at least a portion of the inner walls of the storage chamber has been provided with a reflective surface so that at least a portion of the light which has entered the storage chamber will be reflected and detected by the detector.
Such a photometric measuring system is known from DE-OS-2116381. In this document an absorption measuring apparatus for gases is described, wherein a gas is supplied into a storage chamber via porous walls and the storage chamber is closed by a light generator for generating a light beam to interact with the gas in the storage chamber and a detector for detecting a portion of said light beam, reflected by a reflective surface, located on the inner wall of the storage chamber opposite to the generator and the detector. This apparatus is not appropriate to be used for a liquid. Further there is permanent connection between storage chamber, generator and detector, with the consequence that the application of the measuring system is rather limited.
More appropriate photometric measuring systems are known and are used for performing photometric measurements on liquids, particularly on translucent liquids. More specifically this invention relates to a modified way of providing light to a sample and detecting its attenuation in the sample using a photometric measuring system employing a set of storage chambers arranged in a fixed matrix. Such storage chambers are also known as ‘cuvettes’.
Photometric devices employing a set of cuvettes arranged in a fixed matrix are widespread. A generally used matrix arrangement is a microplate with a standard array of 8×12 wells made of an optically transparent material containing the liquid samples to be measured. such microtiter plates are very cheap and can be disposed of after use. Light passes vertically through the wells and its attenuation is detected with a suitable detector. a variety of systems based on these principles is in use. Variations include the number of light detectors, with at one extreme, a single detector and light beam and a mechanism to move the plate such, that each well subsequently is placed in the beam, or alternatively, a fixed plate can be employed and the beam can be moved in a stepwise or continuous fashion from well to well. Another extreme is that each well is placed in a separate beam and has a separate detector, thus allowing truly simultaneous measurements in all wells. Intermediate arrangements are employed where a group of wells, in most cases a row of 8 or 12 wells, are processed simultaneously by 8 or 12 beams and detectors.
Typically such devices consist of a light source, a monochromator to select the desired wavelength of light, an optical system and a detector with associated electronics. Furthermore an often automated system to move the plate and/or beam detector arrangement to enable measurement of all wells separately, can be present.
Devices like these are often employed in the enzymelinked immuno sorbent assay (ELISA) technique. This technique is widely used to detect and/or quantify a large variety of substances in, e.g., academic research, clinical chemistry, environmental chemistry, biotechnology or biochemistry.
Other applications are the measurement of enzyme reactions resulting in the conversion of a substrate into products with different spectral properties. Widely used are chromogenic peptide substrates for the detection of various proteases. Other applications are measurements of inorganic or organic compounds or the detection of particular reaction products of chemical reactions based on their spectral properties.
Due to the arrangement of the well between the light generator and the light detector, the light has to pass the microtiter plate and the range of wavelengths that can be employed is limited by the optical properties of the plate material. Frequently these disposable low cost microtiter plates are made from a transparant polymer, generally polystyrene, limiting their use to wavelengths between about 330-800 nm. Special polymer materials can extend this range to the near ultraviolet from 250 nm onwards. For wavelengths below this wavelength non-disposable microtiter plates with quartz windows exist, such plates are extremely expensive, fragile and not intended for single use and disposal such as is the case with the polymer plates.
The object of the present invention is to provide a photometric measuring system, which provides a solution for the above-referred to problem. Therefore, the photometric measuring system, according to the invention, is characterized in that, the holder is provided with a plurality of storage chambers and that in order to realise a photometric measurement which can be carried out with respect to a liquid in the storage chamber independent of the wavelength of the generated light beam, each storage chamber has an upper open end and the generator as well as the detector can be arranged at a predetermined distance above said upper open end, such that the light in the lightpath between the light generator and the detector does not meet any physical window.
Hence, in accordance with the present invention the light to be measured does not have to pass the material of the holder. Therefore, the storage chamber, according to the invention, can be made from low cost material, such as for example, polystyrene or polyethene. In accordance with the present invention the incoming light beam enters a storage chamber through its open end, interferes with the liquid present in the storage chamber, reflects on the reflecting surface back to the open end and subsequently leaves the storage chamber so that it can be detected by the light detector.
REFERENCES:
patent: 4004150 (1977-01-01), Natelson
patent: 4498780 (1985-02-01), Banno et al.
patent: 21 16 381 (1972-10-01), None
patent: 40 21 855 A1 (1992-01-01), None
patent: 0 046 430 A1 (1982-02-01), None
patent: 0 545 284 A1 (1993-06-01), None
patent: WO 93/20612 (1993-10-01), None
Font Frank G.
Hoffmann & Baron , LLP
Merlino Amanda
Nederlandse Organisatie voor Toegepast-Natuurwetenschappelijk
LandOfFree
Photometric measuring system and a holder for such a system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photometric measuring system and a holder for such a system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photometric measuring system and a holder for such a system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2552341