CMOS Sensor, image source
The electronic nose has been coming forever. We already have artificial noses in the form of mass spectrometers. The new kind use integrated circuits, the same CMOS chips that are in cellphones. They aren’t tied to a thinking, feeling human, but at least the initial step of identification is happening.
This article in particular is touting the use of an artificial nose to analyze breath samples, citing that “breaths contain gases from the stomach and that come out of blood when it comes into contact with air in the lungs. The breath test is a blood test without taking blood samples. Breath contains information about practically every part of a human body.”
This is good stuff, and explains why your breath starts to smell funny when you’re hungry, or why diabetic-breath smells like acetone, but I must keep going and repeat the sales pitch of this scientist:
"If you think about the industry around sensors that emulate our senses, it's huge," said Dr. O, also a professor in the Erik Jonsson School of Engineering and Computer Science and holder of the Texas Instruments Distinguished University Chair. "Imaging applications, hearing devices, touch sensors—what we are talking about here is developing a device that imitates another one of our sensing modalities and making it affordable and widely available. The possible use of the electronic nose is almost limitless. Think about how we use smell in our daily lives."
But yes, let’s think for a minute about how we use smell in our daily lives. Smell is so below the radar that we don’t consciously register most of its ongoings. So when we take this CMOS sensor to a brain, what exactly would we like it to do? Of course we can’t engineer the olfactory bulb itself, or the subsequent limbic system (in concert with our memory) that ultimately creates our experience of smell. But if we were to isolate it, and use it for specific things, like breath analysis, then what else would it do?
Gas leaks, obviously. Maybe it could alert my roommate to change the litter box? Or tell a parent that their teenager was drinking last night (that’s a simple breathalyzer built into the air system of the house; watch out kids). You would think we’d already have one to smell the maple syrup smell coming from the burning transmission fluid in your engine. And what else? Can I smell the presidential candidates with my CMOS supernose? Who knows. Smell a house on Zillow? Let’s bring it to Japan and see what they do with it.
On thinking about this further, I must stress the difference between what I’ll call active smelling and passive smelling. What we do as humans is passive smelling. For the most part, we are not actively looking for a particular smell. (And, in fact, this is no way to smell, unless you’re a fragrance artist.) It’s more like the Tao of Perception – you must have a “soft awareness” where you are ready for any smell, but you’re not actively smelling for anything in particular. That’s just the way smell works. So this is passive smelling.
Active smelling would be a sensor fitted for one particular odor compound. Acetone, for diabetic-breath, for example. Or it may be fit for a bunch of things on top of that. But you could never fit the sensor for all potential smells. That’s not how the human epithelium works. We would need an artificial olfactory bulb for that, because the bulb turns our 450 receptors into the trillion potential smells available. And further, to attach that to meaning, we would need, again as mentioned above, an entire body, and more than that, a body that has lived from birth. A Frankenstein created at 20 years old would not be able to smell. This must be a baby Frankenstein we’re talking about here, zygote even.
In closing, we can’t have an electronic nose that is “open ended.” It can look for particular things on Zillow – mold? Wet paint? (who cares) Frito Feet? (that’s the smell of dog feet, which could indicate a pet lived in the house?). Thanks for listening.
phys.org, June 2016