Parts per billion gas detection achieved with interferometric device
DOI: 10.1063/10.0001798
Parts per billion gas detection achieved with interferometric device lead image
Gas sensing is a crucial technology for a broad array of applications, from breath analysis to pollution control, many of which can benefit from the miniaturization of the technology. To accommodate the demand for portable gas sensors, Antonacci et al. created a photonics-based device by utilizing the gas-induced refractive index change in silicon nitride waveguides.
The authors constructed the device using an interferometer comprised of a SiN waveguide. Light travels along the waveguide’s reference arm and sensing arm, the latter of which is coated with a special mesoporous layer for increased sensitivity. The presence of gas particles would alter the refractive index along the sensing arm and cause detectable changes in the spectral interference pattern.
“There are no voltages or currents running through the exposed layers, only light,” said author Jeroen Goyvaerts. “Depending on the application, this can improve biocompatibility or even reduce spark hazards in combustible environments.”
To evaluate the sensitivity of the sensor, the authors exposed it to acetone, isopropyl alcohol and ethanol vapors at varying concentrations, and the results showed its capability of sensing the presence of gases on the order of parts per billion. They also tested the sensor’s stability against temperature and humidity fluctuations.
“What makes this research so powerful is the fact that we were able to obtain these results using a very compact photonic chip,” said author Giuseppe Antonacci.
By controlling the pore sizes in the coating during the deposition process, the sensing method can be extended to a wide range of gases, opening the door to additional applications beyond biological and safety sensing.
Source: “Ultra-sensitive refractive index gas sensor with functionalized silicon nitride photonic circuits,” by Giuseppe Antonacci, Jeroen Goyvaerts, Haolan Zhao, Bettina Baumgartner, Bernhard Lendl, and Roel Baets, APL Photonics (2020). The article can be accessed at https://doi.org/10.1063/5.0013577 .
