Accessible Navigation. Go to: Navigation Main Content Footer

Vice President for Research & Development


Project TitleCalibration-free Optical Chemical Sensors
Track Code1999-002
Short Description

Performs absorbance-based measurements without the need to recalibrate the sensors.


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 absorbance’s 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.

Tagsco2, ph, pCO2, pO2, chemical sensor, oceanography, ocean research, submersible, measurement, sensor, wavelength
Posted DateNov 15, 2010 6:26 PM

Technology Overview

This technology’s value comes from its ability to perform absorbance-based measurements without the need to recalibrate the sensors. This allows users to track conditions remotely, over the long-term, and in conditions where recalibration is not practical. 

  • Inventors: Michael D. DeGrandpre, Terry Hammar
  • Intellectual Property Status: Patented
  • Licensing Status: Sub-Licensing Available

More information about the technology is available on the Google Patents:

Licensing Contact

Interested in this technology? Contact the University of Montana, Office of Technology Transfer: BusinessDevelopment.OTT@mso.umt.edu406.243.6670

Office of Technology Transfer

Director - Joe Fanguy

(406) 243-2148