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Title: Calibration-free optical chemical sensors

Abstract

An apparatus and method for taking absorbance-based chemical measurements are described. In a specific embodiment, an indicator-based pCO 2 (partial pressure of CO 2) sensor displays sensor-to-sensor reproducibility and measurement stability. These qualities are achieved by: 1) renewing the sensing solution, 2) allowing the sensing solution to reach equilibrium with the analyte, and 3) calculating the response from a ratio of the indicator solution absorbances which are determined relative to a blank solution. Careful solution preparation, wavelength calibration, and stray light rejection also contribute to this calibration-free system. Three pCO 2 sensors were calibrated and each had response curves which were essentially identical within the uncertainty of the calibration. Long-term laboratory and field studies showed the response had no drift over extended periods (months). The theoretical response, determined from thermodynamic characterization of the indicator solution, also predicted the observed calibration-free performance.

Inventors:
Publication Date:
Research Org.:
Univ. of Montana, Missoula, MT (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1175700
Patent Number(s):
7,026,165
Application Number:
09/775,386
Assignee:
University Of Montana OSTI
DOE Contract Number:  
FG03-94ER6224
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

DeGrandpre, Michael D. Calibration-free optical chemical sensors. United States: N. p., 2006. Web.
DeGrandpre, Michael D. Calibration-free optical chemical sensors. United States.
DeGrandpre, Michael D. Tue . "Calibration-free optical chemical sensors". United States. https://www.osti.gov/servlets/purl/1175700.
@article{osti_1175700,
title = {Calibration-free optical chemical sensors},
author = {DeGrandpre, Michael D.},
abstractNote = {An apparatus and method for taking absorbance-based chemical measurements are described. In a specific embodiment, an indicator-based pCO2 (partial pressure of CO2) sensor displays sensor-to-sensor reproducibility and measurement stability. These qualities are achieved by: 1) renewing the sensing solution, 2) allowing the sensing solution to reach equilibrium with the analyte, and 3) calculating the response from a ratio of the indicator solution absorbances which are determined relative to a blank solution. Careful solution preparation, wavelength calibration, and stray light rejection also contribute to this calibration-free system. Three pCO2 sensors were calibrated and each had response curves which were essentially identical within the uncertainty of the calibration. Long-term laboratory and field studies showed the response had no drift over extended periods (months). The theoretical response, determined from thermodynamic characterization of the indicator solution, also predicted the observed calibration-free performance.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Apr 11 00:00:00 EDT 2006},
month = {Tue Apr 11 00:00:00 EDT 2006}
}

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