This article describes a small prototype sensor designed to sense carbon dioxide (CO₂) levels for indoor air quality monitoring. The device uses a photoacoustic detector fabricated using a wafer-bonding process. This allows for high-volume production of the sensors. The prototype presented is small in size and can detect CO₂ levels as low as 81 ppm with a response time of 53 s. Our results show suitability for application in indoor air quality control systems.

Imaging of greenhouse gases is of great interest due to global warming. A spectroscopic method, using an active illumination of the scene, is presented. It allows for imaging and concentration measurements of much smaller gas plumes and leaks than current state-of-the-art gas cameras (optical gas imaging cameras). A real-time camera is realized and validated using known methane concentrations.

We present a photoacoustic sensor enabling fast, inexpensive, and highly sensitive methane detection in environmental monitoring applications. Six different T-cell designs were both theoretically and experimentally investigated. The aim was to understand the photoacoustic signal generation and resonances in relation to the different cell geometries, and determine the long-term stability and the detection limits for methane. These were below the methane background concentration in air of 1.8 ppm.

Detection of flammable gases is necessary to avoid explosive atmospheres. Commercial pellistors require an operation temperature above 450 °C for the detection of methane. We present a novel wireless low-power catalytic gas sensor system based on non-precious metal catalyst for the detection of methane and propane operated at 350 °C. The combination of a MEMS-based sensor with a low-power radio system provides the opportunity to monitor complex infrastructures without using a power grid.