Optics: measuring and testing – With sample preparation
Patent
1999-05-04
2000-08-08
Kim, Robert H.
Optics: measuring and testing
With sample preparation
356 39, 356244, G01N 100
Patent
active
061009660
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a test device for bodily fluids comprising a solid carrier with a bonded reagent, a light source for transmitting light to the carrier and a light detector for detecting light received from the carrier.
Such test devices are well known in the art. U.S. Pat. No. 5,131,756 discloses a test carrier analysis device for determining the reflectivity of a test field surface. An optical unit of the device contains several light transmitters and a measurement receiver, whereby the light transmitters are directed obliquely from above onto the measurement surface. The light transmitters are arranged opposite to one another with off-set planes of incidence.
Other test devices known in the art employ light sources wherein the light impinges on the measurement surface uniformly from all directions in space. Commonly, the light sources that are used are light-emitting diodes, which are favoured in view of their low-energy use, low costs and high reliability.
Test devices to which the invention relates are particularly useful for pregnancy tests but are not confined hereto. A prime consideration with these test devices is that they must be small, manageable and cheap to manufacture in view of the required suitability for self-diagnosis by a user.
The problem with known devices is the lack of accuracy, particularly in the area where the signals measured by the detector do not warrant an unambiguous positive or negative test result.
SUMMARY OF THE INVENTION
The test device according to the invention aims to provide a cheap, reliable and accurate test device suitable for both home- and professional use. The test device according to the invention is therefore characterized in that in use the light source transmits light to the carrier in a direction suitable to cause the substance of the light to enter the carrier. Contrary to any test device known in the art, the test device according to the invention is not based on the reflection of light transmitted to a carrier-surface by the detector, but is based on a quite distinct principle; i.e. the test device according to the invention realises a prolonged path for the light imparted in the carrier's interior for travelling to the detector. Along that path in the interior of the carrier the light is scattered and diffused allowing for an increased interaction through absorption of the light by such area of the carrier where a sample of bodily fluid has entertained a reaction with the reagent bonded in the carrier. Due to this measure the sensitivity and accuracy for measuring the occurrence and the extent of any such reaction is highly increased. This is particularly supported by assuring that in use the substance of the light received by the detector is received from the carrier.
A further increased sensitivity of the test device can be accomplished by covering the carrier at least partly by a reflective foil or coating. The coating may be provided on one side or on all sides, but in all cases it is required that the carrier is at least partly covered by a reflective foil or coating and that this reflective foil or coating is locally absent near the light source and the detector, to allow light to travel to and from the carrier.
The reaction of the carrier bonded reagent with the sample of bodily fluid, is particularly supported when the carrier is porous, providing therewith a large surface/volume ratio so that an effective reaction within a confined area is enabled, and the effective propagation of light through the carrier is promoted. Very suitable materials for the carrier can be selected from the group comprising silica paper, polyethylene, nitrocellulose, glass beads, etc.
Practice has shown that the distance between light source and detector can be kept at a moderate value in the range of 1-5 mm. The sensitivity of the test device for the light transmitted by the light source is improved by the application of blocking means to prevent the light to travel directly from the light source to the detector. In practice, t
REFERENCES:
patent: 5131756 (1992-07-01), Schmidt et al.
Akzo Nobel N.V.
Kim Robert H.
Muir Gregory R.
Natividad Phil
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