Measuring and testing – Gas analysis – Detector detail
Reexamination Certificate
1999-11-15
2001-07-31
Williams, Hezron (Department: 2856)
Measuring and testing
Gas analysis
Detector detail
C073S023200, C422S083000, C422S082090, C422S051000, C422S051000, C422S088000, C436S167000
Reexamination Certificate
active
06266998
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a system for measuring the concentration of gases using gas-selective, optically detectable indicator substances in a chip-like carrier wherein the change in the indicator substances is detected by means of an optoelectronic scanning device.
BACKGROUND OF THE INVENTION
Such a system has become known from DE 39 02 402 C1. One drawback of this prior-art arrangement is that the gas-sensitive indicator layer is scanned optically in a punctiform manner only, so that the measuring sensitivity is relatively low.
SUMMARY AND OBJECTS OF THE INVENTION
The object of the present invention is to provide a system of the type described in the introduction, which has increased measuring sensitivity and makes it possible to cover broader concentration ranges of the gases to be measured.
According to the invention, a system is provided for measuring the concentration of gases using gas-selective, optically detectable indicator substances in a chip-like carrier. The change in the indicator substances is detected by means of an optoelectronic scanning device. The chip-like carrier comprises a composite of partial elements wherein one partial element contains channels for guiding the gas in the carrier, and another partial element has at least one multireflection element for guiding light. Each multireflection element is provided with a layer with indicator substances, which layer faces the gases to be measured and reacts with same in a gas-selective manner. The optoelectronic scanning device has at least one radiation source with an associated radiation detector which are in optical functional connection with each multireflection element.
The essential advantage of the system according to the present invention is that despite its highly compact, material-saving design, it makes it possible to reach a substantially improved signal sensitivity and can be used in a versatile manner in terms of both different gases to be measured and different gas concentrations to be measured.
One essential component of the present invention is represented by the multireflection elements used with a layer containing optically detectable indicator substances, which layer faces the gases to be measured and reacts in a gas-selective and concentration-dependent manner. These multireflection elements are usually flat carriers made of optical materials, such as glass or a transparent plastic, which are provided with the said gas-sensitive layer on the top side. This layer is applied especially in the form of a solution or a dispersion, especially preferably as a colloid-disperse solution. Prior-art techniques for the application are especially spin coating, dip coating or inkjet metering. The function of the gas-sensitive layers is based on colorimetric reactions, i.e., the contact and the subsequent reaction with the gas to be measured lead to a change in color in the layer.
The degree of change in light transmission along the multireflection element is subsequently detected with a radiation detector by means of the light emitted by a radiation source, designed, e.g., as a diode (LED), the light being coupled in on one front side of the multireflection element at right angles to the oblique front surface. Based on multiple total reflection at the interfaces to the ambient air, the light coupled in passes through the gas-selective indicator layer a corresponding number of times. The light is again uncoupled on the opposite, likewise oblique front surface and is converted by a radiation detector, which is designed, e.g., as a photodiode, into an electric signal, which is subjected to further processing in an evaluating and calculating unit and is, in particular, displayed. Both the intensity of the change in the color of the gas-selective indicator layer and the time to a defined change in intensity may be used to evaluate the signals.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
REFERENCES:
patent: 4608344 (1986-08-01), Carter et al.
patent: 4872759 (1989-10-01), Stich-Baumeister et al.
patent: 5059396 (1991-10-01), Opitz et al.
patent: 5089232 (1992-02-01), May
patent: 5397538 (1995-03-01), Stark et al.
patent: 5415838 (1995-05-01), Rieger et al.
patent: 5464588 (1995-11-01), Bather et al.
patent: 5538850 (1996-07-01), King et al.
patent: 5998221 (1999-12-01), Malick et al.
patent: 6024923 (2000-02-01), Melendez et al.
patent: 6096560 (2000-08-01), Scripca et al.
patent: 39 02 402 C1 (1990-06-01), None
Skoog, D.A. Principles of Instrumental Analysis, 1984, pp. 160-163.
Cygan Michael
Dragerwerk Aktiengesellschaft
McGlew and Tuttle , P.C.
Williams Hezron
LandOfFree
System for measuring the concentration of gases does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System for measuring the concentration of gases, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System for measuring the concentration of gases will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2489111