I find it interesting that we seem to have mastered what the human eye can do and even go beyond it with like infrared but somehow we still can't build a chip that can "taste" or "smell".
MOX sensors (like the SnO2 in this paper) have been around for decades but hit a fundamental ceiling—they require specific coatings to bind to specific VOCs. Want to detect a new substance? You're changing hardware.
The more promising path, IMO, is carbon nanotube (CNT) sensors that actually mimic how our nose works. Instead of measuring bulk resistance changes, you functionalize CNT arrays to respond to specific molecular binding events—much closer to how olfactory receptors operate. detection of new substances becomes a software/ML problem rather than a hardware redesign. That's how biology does it—your nose doesn't grow new receptors, your brain learns new patterns.
Full disclosure: I'm building in this space (https://nosy.network) Nosy is using CNT paired with transformer models to create what we call a "Large Essence Model" (LEM). LEM "GPT for smell" processes scent information similar to how LLMs process text.
The challenge is piecing together what you have detected to draw conclusions about the sample - in this instance you might detect a specific molecule, but to definitively conclude that it's caused by a particular fungus requires lots of prior testing.
Vision is "easy": What I see is what you see is what the machine sees.
A machine shows us what it sees and we can verify that it is working correctly, with a glance.
How would we verify that a machine smells or tastes "correctly"?
I'm no olfactory biochemist, but that sounds like science-fiction to me. The, er, reference implementation we're talking about is advanced nanotechnology we don't fully understand.
While we can do stuff like mass-spectrography, that involves destroying complex chemicals and converting them to smaller fragments we can tally, and then guessing at possible configurations they might have originally had.
If someone had a device that could simply tell you the exact chemical formulas of all molecules of any kind in a sample, it would be used everywhere and they would be very rich.
This would be a very large machine and you would need to provide a sample to it in a test tube or similar manner. Automated blood analyzers in hospitals are maybe the closest thing to a such device.
I dont say such machines don't exist, but for my taste (pun intended) the solutions all lack something, either long term stability or having a second source supplier or being able to classify a reasonable amount of tastes or being able to distinguish between two tastes (or lacking all those things together).
OTOH maybe dogs are cheap enough not to create strong incentive for automation.
- "oh, so you have no sense of smell?"