Medical-analytical gas detector
First Claim
1. A device for detecting a component gas in a sample gas comprising:
- a housing;
source means mounted within the housing for providing radiation in a preselected spectral band having at least one absorption line of the component gas to be detected;
detector means mounted in the housing for detecting radiation in the preselected spectral band;
a plurality of reference cells, each reference cell containing a reference gas including a standard amount of said component gas to be detected;
a sample cell for containing a quantity of sample gas including the component gas to be detected; and
sequencer means in the housing for introducing in time sequence each of the reference cells and also the sample cell into an optical path between the source means and the detector means;
means for providing access to the sample cell for at least the component gas to be measured from a region of the skin surface of the body when the device is brought into intimate contact with said region;
said detector means being responsive to radiation incident thereon when each of the reference cells is in the optical path and when the sample cell is in the optical path, for producing thereby a plurality of detector output signals whose amplitudes are dependent on the amount of the component gas which may be present in the plurality of reference cells and the sample cell respectively, said plurality of signals being operable in predetermined formulation to provide an indication of the concentration of the component gas in the sample gas.
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Accused Products
Abstract
A gas analyzer is provided which is particularly suited for making transcutaneous measurement of the CO2 concentration in the blood.
In accordance with one embodiment of the invention, sample gases from the body are circulated in a cavity of the device. A rotating wheel in the cavity includes two reference cells and a sample cell which are sequentially rotated into the optical path between a source and a detector. Three signals are thereby provided which may be combined to give an output indication of the CO2 concentration in the body fluids. In a preferred embodiment, the sample cell is an "inverted cell" being in open communication with the sample gas circulating in the device so that the gas in the sample cell is a portion of the circulating gas which also surrounds the two reference cells. An output indication is thereby obtained which is insensitive to contaminants in the sample.
In accordance with another embodiment, the sample cell is isolated from the region surrounding the wheel and positioned so as to be presented in series with the reference cells in the optical detection path.
In preferred embodiments, the rotating wheel contains a number of permanent magnets which interact with a number of electromagnets driven in sequence to provide rotation of the wheel.
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Citations
12 Claims
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1. A device for detecting a component gas in a sample gas comprising:
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a housing; source means mounted within the housing for providing radiation in a preselected spectral band having at least one absorption line of the component gas to be detected; detector means mounted in the housing for detecting radiation in the preselected spectral band; a plurality of reference cells, each reference cell containing a reference gas including a standard amount of said component gas to be detected; a sample cell for containing a quantity of sample gas including the component gas to be detected; and sequencer means in the housing for introducing in time sequence each of the reference cells and also the sample cell into an optical path between the source means and the detector means; means for providing access to the sample cell for at least the component gas to be measured from a region of the skin surface of the body when the device is brought into intimate contact with said region; said detector means being responsive to radiation incident thereon when each of the reference cells is in the optical path and when the sample cell is in the optical path, for producing thereby a plurality of detector output signals whose amplitudes are dependent on the amount of the component gas which may be present in the plurality of reference cells and the sample cell respectively, said plurality of signals being operable in predetermined formulation to provide an indication of the concentration of the component gas in the sample gas. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification