Air quality monitoring is a major issue for public health. While wearable fitness trackers can track many health parameters, access to air quality data remains limited. Physicists from ARC (Center of Excellence for Transformative Meta-Optical Systems) are working on an innovative solution: portable infrared micro-spectrometers that could be integrated into portable devices.
This new technology, developed by the team from the University of Melbourne, uses a machine learning algorithm and metasurface spectral filter arrays to create a microspectrometer (MIMM) capable of detecting the unique infrared signature of multiple gases using a single sensor.
The prototype, currently the size of a matchbox, has the potential to be even more miniaturized. Traditional infrared spectrometers are excellent gas detectors, but they are bulky and usually reserved for laboratories. Current portable multi-gas detectors are composed of several bulky sensor systems in a single housing, which limits their usefulness.
Metasurface filters for efficient miniaturization
A metasurface filter integrated into a standard IR detector solves miniaturization problems by creating sensors from materials just a few nanometers thick. TMOS researchers created an array of metasurface spectral filters to create a sensor capable of detecting all harmful gases.
The filter array consists of metal nanostructures on a silicon substrate. By varying the periodicity of the nanostructures, the spectral characteristics of these filters can be tuned in the wavelength of interest. In this study they demonstrated its effectiveness with carbon dioxide, methane, ammonia and methyl ethyl ketone.
Towards an application to other chemical detection problems
According to Jiajun Meng, lead author of the study, “the microspectrometer is a metasurface filter array integrated into a commercial IR camera, compact (~1 cm3) and lightweight (~1 g). The machine learning algorithm is trained to analyze the microspectrometer data and predict the gases present.»
Kenneth Crozier, TMOS chief researcher, adds: “The next steps in the research are to increase the sensitivity of the device and make the platform more robust. We are excited about this technology because, with a little more development, it can be applied to many other chemical sensing problems (e.g., solids and liquids).»
Article: “Smart mid-infrared metasurface microspectrometer gas sensing system” – DOI: https://www.nature.com/articles/s41378-024-00697-2
