Physicists at the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS) have developed a portable infrared (IR) micro-spectrometer that could one day be integrated into wearable devices.
The technology, which aims to improve access to air quality data, may provide consumers with the ability to monitor multiple toxic and greenhouse gases, giving individuals increased control over their own exposure so they can make better-informed decisions about their health.
Details of the development and testing of the technology’s effectiveness, reported in Microsystems and Nanoengineering, reveal how the infrared micro-spectrometer uses a machine learning algorithm as well as metasurface spectral filter arrays to create a microspectrometer (MIMM). The MMM detects the unique infrared signature of multiple gases – such as carbon dioxide, methane, ammonia and methyl-ethyl-ketone – using a sensor.
Jiajun Meng, lead author on the paper, said: “The microspectrometer is a metasurface filter array integrated with a commercial IR camera that is consumable-free, compact and lightweight. The machine learning algorithm is trained to analyse the data from the micro-spectrometer and predict the gases present.”
The prototype of this technology is currently the size of a matchbox, and even has the potential to be miniaturised further, making it more usable for consumers compared to traditional infrared spectrometers which are usually bulky and only found in laboratories.
Current portable multi-gas detectors, such as those used in homes and office buildings, are also limited in their usefulness due to their bulk sensor systems which increased the size and weight of the device. These devices use chemiresistors rather than spectroscopy, resulting in inferior results and limiting their lifespan.
On the other hand, the technology developed by the researchers, comprised of a metasurface filter with an integrated off-the-shelf IR detector, addresses the issues of miniaturisation by creating sensors from materials on nanometres thick.
The TMOS researchers created a metasurface spectral filter array to create a sensor with the potential to sense all harmful gases. The filter array consists of metallic nanostructures on top of a silicon substrate. By varying the periodicity of the nanostructures, the spectral features of these filters can be tuned in the wavelength of interest.
TMOS Chief Investigator, Kenneth Crozier, commented: “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 lots of other chemical detection problems (e.g. solids and liquids).”
Lead image: National Centre for Atmospheric Science
