The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 12, 1993
Filed:
Aug. 08, 1991
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
An improved optical probe for the invasive measurement of partial carbon dioxide pressures is disclosed that minimizes pCO.sub.2 reading drift. An optical probe for the invasive measurement of the partial carbon dioxide pressure comprises an optical fiber and a pCO.sub.2 sensor. The pCO.sub.2 sensor comprises a diffusion zone with a dye-containing gel that is optically sensitive to H.sup.+ ions and a semi-permeable membrane that is permeable to CO.sub.2 molecules, but is substantially nonpermeable to hydrogen ions Components of the pCO.sub.2 sensor, such as the part of the optical fiber extending into the sensor or a reflector, are covered with a substance--preferably with a coating--that is substantially nonpermeable to hydrogen ions. This prevents the hydrogen ions from diffusing into the sensor components, which otherwise would cause an imbalance of hydrogen ions and, therefore, a drift in the pCO.sub.2 reading.