An Innovative Tool for Isotopic Ratio Measurements, Environmental Monitoring and Gas Sensing for Industrial Process Control

Web Published:

Princeton Docket # 12-2762


Researchers at Princeton University have developed differential optical dispersion spectroscopy (DODiS), a precise trace-gas sensing technology that enables direct optical subtraction of dispersion spectroscopic signals produced by two different gas samples. Princeton is currently seeking industrial collaborators to commercialize this technology.



- Truly optical subtraction of spectroscopic signals

- Direct sensing of concentration differences, also for highly absorbing samples

- Selective suppression of unwanted background spectral features

High concentration dynamic range


Isotopic ratio measurements

Medical (e.g. breath test)

Pharmaceutical (e.g. batch quality control, and product identification)

Research in the fields of Environmental Science, Ecology, Geochemistry, and Archaeology

Industrial monitoring (e.g. methane detection in the presence of interfering gases such as propane or butane etc.)


Background: DODiS technique was developed to address two challenges in gas sensing applications. First is differential/comparative analysis of two samples that is often used to perform precise molecular detection, e.g. in isotope ratio measurements when gas under test is compared with a reference standard, preferably at the same time and in the same conditions. Strategies that are typically applied require using two separate optical paths (one for measured sample and one for reference) or sample and reference gases are flown through single-path setup and measured alternately. As a result two samples can be measured at the same time but not in the same conditions or in similar conditions but not simultaneously. Second challenge addressed by DODiS is gas detection in the presence of strong interference from other species that frequently occurs in environmental or industrial monitoring. Very often such interference cannot be easily suppressed, which requires selection of other spectral signatures of the target molecule that may lead to significant reduction of system performance.


Description of Technology: DODiS technology enables direct comparison of the two gas samples under the same conditions using a single laser source and a single photodetector. Two samples are measured simultaneously producing absorption and dispersion signals. The absorption and dispersion spectra provide information about the sum and the difference of molecular concentrations in both samples from which concentration of each sample can be easily deduced. With DODiS, improvement in long-term stability and reduction of measurement errors in applications that require comparison of two samples (e.g. gas under test and reference gas) are expected.

Moreover, since DODiS enables selective subtraction of spectroscopic signal, it can be also used for suppression of unwanted interfering background spectral features (e.g. interference from water vapor that is often observed in environmental monitoring).


The Inventors

Gerard Wysocki is an assistant professor of Electrical Engineering. His current research interests focus on the development of novel laser-based spectroscopic systems for chemical sensing in various applications including environmental monitoring, bio-medical research, and industrial process control. Among many distinguished awards most recently Professor Wysocki has been named finalist of the Blavatnik Awards for Young Scientists (2011), received NSF Early Career Award (2010), Masao Horiba Award (2010, Japan), and NASA Tech Brief Award for Scientific or Technical Innovation (2010).

Michal Nikodem is currently a postdoctoral research associate in Electrical Engineering Department at Princeton University working with professor Wysocki. He has expertise in development of optical frequency comb sources and femtosecond fiber lasers for precise metrology and spectroscopy. In 2009 and 2010 he was with Menlo Systems GmbH where he carried out research on broadband THz spectroscopy. His current research interests include new laser-based dispersion sensing techniques for in-situ and remote chemical detection.


Intellectual Property status
Patent protection is pending.

Michael Tyerech
Princeton University Office of Technology Licensing  (609) 258-6762


Patent Information:
For Information, Contact:
Chris Wright
Licensing Associate
Princeton University
Michal Nikodem
Gerard Wysocki