Carbon dioxide sensor
First Claim
Patent Images
1. A sensor for determining the partial pressure of carbon dioxide in a liquid, which comprises a carbon dioxide permeable, liquid and ion impermeable membrane enveloping a transparent aqueous gel which exhibits variations in pH as a function of the partial pressure of dissolved carbon dioxide, said aqueous gel containing:
- (i) from 5×
10-5 M to 1×
10-3 M of an absorber whose absorption spectrum exhibits peaks at wavelengths λ
A and λ
B and whose absorbances at λ
A and λ
B are pH-dependent;
(ii) a fluorescer having a fluorescent emission spectrum with a peak at wavelength λ
F and an excitation spectrum with a peak at wavelength λ
X and whose fluorscent intensities at λ
F and λ
X are pH-independent; and
(iii) a source of bicarbonate ions which provides bicarbonate ions in a concentration which maintains the pH of the aqueous gel in the range of maximum response of the absorber;
wherein the ratio of fluorescer to absorber is in the range from 0.4;
1 to 10;
1, and there is sufficient overlap between the peaks at wavelength λ
F or λ
X of the emission and excitation spectra of the fluorescer and the peaks at wavelength λ
A or λ
B of the absorption spectrum of the absorber so that the partial pressure of carbon dioxide in the liquid may be determined from the pH of the aqueous gel as measured by the intensity of fluorescent emission at λ
F.
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Abstract
A sensor for determining the partial pressure of carbon dioxide in a liquid, which comprises a carbon dioxide - permeable, liquid and ion-impermeable membrane enveloping an aqueous medium containing an absorber, a fluorescer and a source of bicarbonate ions, which medium exhibits variations in pH as a function of the partial pressure of dissolved carbon dioxide, the ratio of absorber to fluorescer and the characteristics of the absorption spectrum of the absorber and the excitation and emission spectra of the fluorescer being such that the partial pressure of carbon dioxide in the liquid may be determined from the pH of the aqueous medium as measured by the intensity of the fluorescent emission of the fluorescer.
77 Citations
14 Claims
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1. A sensor for determining the partial pressure of carbon dioxide in a liquid, which comprises a carbon dioxide permeable, liquid and ion impermeable membrane enveloping a transparent aqueous gel which exhibits variations in pH as a function of the partial pressure of dissolved carbon dioxide, said aqueous gel containing:
- (i) from 5×
10-5 M to 1×
10-3 M of an absorber whose absorption spectrum exhibits peaks at wavelengths λ
A and λ
B and whose absorbances at λ
A and λ
B are pH-dependent;
(ii) a fluorescer having a fluorescent emission spectrum with a peak at wavelength λ
F and an excitation spectrum with a peak at wavelength λ
X and whose fluorscent intensities at λ
F and λ
X are pH-independent; and
(iii) a source of bicarbonate ions which provides bicarbonate ions in a concentration which maintains the pH of the aqueous gel in the range of maximum response of the absorber;
wherein the ratio of fluorescer to absorber is in the range from 0.4;
1 to 10;
1, and there is sufficient overlap between the peaks at wavelength λ
F or λ
X of the emission and excitation spectra of the fluorescer and the peaks at wavelength λ
A or λ
B of the absorption spectrum of the absorber so that the partial pressure of carbon dioxide in the liquid may be determined from the pH of the aqueous gel as measured by the intensity of fluorescent emission at λ
F. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- (i) from 5×
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9. A sensor for determining the partial pressure of carbon dioxide in a liquid, which comprises a carbon dioxide-permeable, liquid and ion-impermeable membrane enveloping an aqueous medium which exhibits variations in pH as a function of the partial pressure of dissolved carbon dioxide, said aqueous medium containing:
- (i) from 5×
10-5 M to 1×
10-3 M of an absorber whose absorption spectrum exhibits peaks at wavelengths λ
A and λ
B and whose absorbances at λ
A and λ
B are pH-dependent;
(ii) fluorescer having a fluorescent emission spectrum with a peak at wavelength λ
F and an excitation spectrum with a peak at wavelength λ
X and whose fluorescence intensities at 80 F and λ
X are pH-independent; and
(iii) a source of bicarbonate ions which provides bicarbonate ions in a concentration which maintains the pH of the aqueous medium in the range of maximum response of the absorber;
wherein said absorber or fluorescer or both said absorber and fluorescer is bound to a polymer and the ratio of fluorescer to absorber is in the range from 0.4;
1 to 10;
1, and there is sufficient overlap between the peaks at wavelength λ
F or λ
X of the emission and excitation spectra of the fluorescer and the peaks at wavelength λ
A or λ
B of the absorption spectrum of the absorber so that the partial pressure of carbon dioxide in the liquid may be determined from the pH of the aqueous medium as measured by the intensity of fluorescent emission at λ
F. - View Dependent Claims (10, 11, 12)
- (i) from 5×
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13. A sensor for determining the partial pressure of carbon dioxide in a liquid, which comprises a carbon dioxide-permeable, liquid and ion inpermeable membrane enveloping an aqueous medium which exhibits variations in pH as a function of the partial pressure of dissolved carbon dioxide, said aqueous medium containing:
- (ii) from 5×
10-5 M to 1×
10-3 M of an absorber whose absorption spectrum exhibits peaks at wavelengths λ
A and λ
B and whose absorbances at λ
A and λ
B are pH-dependent, said absorber being selected from the group consisting of 2,6-dimethyl-4-nitrophenol and methyl (2-nitro-5-hydroxy) benzoate;
(ii) a fluorescer having a fluorescent emmission spectrum with a peak at wavelength λ
F and an excitation spectrum with a peak at wavelength λ
X and whose fluoresence intensities at λ
F and λ
X are pH-independent, said fluorescer being 6,7-dimethoxycoumarin when said absorber is 2,6-dimethyl-4-nitrophenol and said fluorescer being dimethyl (2,2'"'"'-bifuran-5,5'"'"'-dicarboxylate) when said absorber is methyl (2-nitro-5-hydroxy) benzoate; and
(iii) a source of bicarbonate ions which provides bicarbonate ions in a concentration which maintains the pH of the aqueous medium in the range of maximum response of the absorber;
wherein the ratio of fluorescer to absorber is in the range from 0.4;
1 to 10;
1, and there is sufficient overlap between the peaks at wavelength λ
F or λ
X of the emission and excitation spectra of the fluorescer and the peaks at wavelength λ
A or λ
B of the absorption spectrum of the absorber so that the partial pressure of carbon dioxide in the liquid may be determined from the pH of the aqueous medium as measured by the intensity of fluorescent emission at λ
F. - View Dependent Claims (14)
- (ii) from 5×
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Current AssigneeMedtronic Minimed Incorporated (Medtronic Plc)
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Original AssigneePfizer Hospital Products Group, Inc. (Pfizer Inc.)
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InventorsMatthews, Richard S., Witherell, Frederick E. Jr.
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Primary Examiner(s)Hill, Jr., Robert J.
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Assistant Examiner(s)Griffith, Rebekah A.
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Application NumberUS07/086,423Time in Patent Office708 DaysField of Search422/55, 422/58, 422/59, 422/68, 435/807, 435/808, 436/68, 436/133, 436/163, 436/164, 436/167, 436/172, 436/178, 128/632-634, 128/653, 128/666, 204/400, 204/415, 204/433, 250/373, 250/458.1, 250/459.1, 250/461.1, 356/39, 356/40, 356/402, 356/441US Class Current422/82.07CPC Class CodesG01N 2021/0385 Diffusing membrane; Semiper...G01N 21/643 non-biological materialG01N 21/80 Indicating pH valueY10T 436/204998 Inorganic carbon compoundsY10T 436/255 including use of a solid so...
