Enhancement of Hydrogen Sensing with Multi-reflection Raman Scattering

It is of great interest to detect hydrogen for safety in the hydrogen society. The present study reports on a sensor based on Raman Scattering for the detection of hydrogen gas. By using multiple reflections of the excitation laser beam, the sensitivity of detecting hydrogen by Raman scattering was enhanced about 35 times as compared to a previous single laser beam. Therefore, the detection limit of hydrogen concentration was measured and found to be about 0.1 vol. %, which was better than the previously reported one of 0.6 vol. %, using a single laser beam. Additionally, the unique point of using Raman scattering for gas sensing is that each kind of gas has a different Raman wavelength; therefore, it is possible to detect multiple kinds of gases in the same system, and with no malfunction alert like the popular conventional catalytic hydrogen sensor, which senses other flammable gases. Raman sensor also operates with a fast response time and has no effect from water vapor such as in very high humidity environment. Actually, many sensors cannot be operated in nearly 100% humidity.