Gas sensors are usually engineered to detect a specific molecule in one of many potential categories: toxic gases, combustible gases, VOCs. A number of technologies, such as infrared, photoionization, catalytic and electrochemical, are used to test for differing molecular species. Each method has different specifications for resolution, sensitivity, temperature, and humidity range. Gas sensors are most useful with flexibility in gases detected and high sensitivity.
LLNL researchers have combined Raman and infrared (IR) spectroscopy methods in a single device. The sensor is able to detect, identify, and quantify a range of unknown gases. Raman spectroscopy records the degree of light scattered while IR measures the amount of light that is absorbed. The combination of the two techniques results in complementary spectra that serve as molecular-level fingerprints of gaseous species. With this sensor, gas concentrations down to the parts-per-million, and even parts-per-billion, can successfully be detected and measured. The device can be miniaturized for easy deployment.
- Optical sensor → No electrical requirements → Safe for environments involving energetic materials
- Raman/IR combination → Wider gas sensing capability
- Fiber-based multi-pass cells → Sensitivities down to ppm and ppb levels
- Double-pass IR probe → Reduces length and size of the sensor → Allows miniaturization for portability & field deployment
- Can be embedded in confined spaces for continuous monitoring → Lower operating costs
- Continuous monitoring and detection of gases, gas mixtures, identifying and quantification of unknown gas species
- Environmental and pollution monitoring
- Locating victims after natural disasters or attacks based on molecules generated by victims (e.g. exhaled CO2)
- Breath analysis for explosives or radiological exposure assessment in Homeland Security applications
- Breath analysis for detecting diseases in-vitro (e.g. cancer)
Several prototypes have accurately detected common gases in lab tests with additional experiments planned for a wider range of gases. A U.S. Patent application has been filed.