Multifunctional hydrogen and ammonia gas sensors from ScAlN-based pyroelectric detectors towards adoption of sustainable fuels

We demonstrate the use of pyroelectric detectors for development of H2 and NH3 gas sensors based on thermal and optical sensing respectively. A thumb-size H2 purity sensor capable of detecting high concentration of H2 with resolution of 0.1% is developed using ScAlN-based pyroelectric detector. This sensor can detect high concentration H2 up to 100% and can differentiate concentration up to 0.1% at high concentration, presenting different sensing output signals for 99.8% and 99.9% H2. The sensor can measure H2 from 400 ppm–100% concentration and is resistant to moisture up to 95% relative humidity levels. It is suitable to be integrated in-line to H2 production systems such as electrolyzers for real-time monitoring of H2 produced. This H2 purity sensor is also multi-functional: being able to sense He and function as a gas flow sensor sensing down to 50 sccm. For NH3 gas sensor, using ScAlN-based pyroelectric detector, we leverage on NH3 gas absorption at 10-11 μm wavelength and demonstrate NH3 gas sensing from 21ppm to 100 ppm. The development of H2 and NH3 gas sensors will help to contribute to quality monitoring and safer adoption of H2 and NH3 gases as renewable energy with different use cases.