At CES, Taiwanese firm N&M had a really unique use for silicon photonics, gas detection. SemiAccurate had never seen this application but looking at it more deeply makes a lot of sense.
N&M or Taiwan Nano & Micro-Photonics Co, Ltd makes two core products, a silicon light emitter and a detector which can be tuned, filtered, and made into some pretty interesting devices. If you are familiar with how chromatography works, you can probably skip this article. If you are not, the idea is pretty simple, shine light on or through a sample and look at what frequencies are emitted. Since atoms and molecules radiate energy in distinct spectra, with an appropriate detector you get a graph with peaks at various wavelengths. These wavelengths are direct fingerprints of the chemicals in the sample.
This is the same idea with X-rays
While the mechanisms and machinery to do the readings can be pretty complex and touchy, I speak from experience, the readouts are pretty simple. The emission spectra for nearly everything under the sun is known so you just have to match the graph you made with the chemicals you are looking for. My experience here is way out of date but is was easy back then and is probably fully automated now. In any case, spectroscopy is not a trick, preparing the samples and keeping the machinery happy is the hard part.
The chips that power it all
That is where N&M come in. They have four packaged silicon emitters and one detector that can probably cover the needed ranges. The emitters come in various wavelengths from 5.8μ to 7.4μ while there is only one detector part that covers the needed emission spectra.
With a combination of tuning, filters, and training, you can detect a wide range of organic and non-organic molecules. The device N&M was showing at CES was able to sniff out CO2, CO, an alcohol from the air. Sadly we live in modern times so the ambient alcohol levels in the air at the show were near zero. Other uses are medical for detection of various maladies through exhalation of marker chemicals, and many other safety related scenarios.
The device is the little box on the right
How it works is simple enough, it pulls air in, shines a light on it, and looks for specific emission peaks. The peak location shows what is in the air and the height shows the amount of that chemical. Simple and effective really, and N&M did the hard work to enable end user devices. They have taken technology that was once the domain of high end scientific tools and consumerized it.S|A
