We use dogs to sniff for drugs even when the smell is masked or inside of things, they can identify and track a person by their unique smell, and dogs have also been able to smell all sorts of illnesses on people so it’s obviously something that would be incredibly useful but what’s the barrier stopping us from reliably making a versatile odor detector artificially?
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The simple answer is that an artificial nose isn’t a single sensor, or even a large group of a small number of similar sensors (like the eyes: 3-5 different sensor types, just thousands upon thousands of them), but the exact opposite. Each nose is a few hundred to a few thousand of each of over 300 types of sensors. There is an individual sensor for the scent of “orange”, another for “sweet”, and still another for “rancid”. Each of those different smells is associated with its own airborne chemical, and has to finely tuned tuned to detect the chemical (by allowing it to attach to the sensor and produce an electrical signal) and then release from that same sensor after a specific, but variable amount of time. We haven’t even identified all the different sensors (“smells”), yet, let alone the sensors that can detect them AND release them over a short enough time period.
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