What ever happened to nanotechnology? Seems like it disappeared.

It’s still here, but you aren’t seeing it because it’s really small.

It's used in medicine, meta materials, and physics everyday.

This. You just don’t hear the word anymore. For example, it was instrumental in producing the COVID-19 vaccine.
The reason pencils work as well as they do is because of the way they are constructed, of nanomaterials.
- Graphite is now a nano material?

it didn't disappear, just got to small for you to see 😉

Should still be somewhere. Maybe in the carpet or the sofa...

It split into two.

The “very small scale structure manufacturing” part is alive and kicking. You are holding about a trillion perfect nanoscale devices in the palm of your hand right now.

The “we will make tiny robots that live in your body and fix you” club was always selling snake oil-and they knew it. The technology they were pushing just does not work at atmosphere temperature and pressure and immersed in oxidizing not quite neutral pH fluid.

Thankfully, there a much better way to make tiny machines that live in your body. That’s making/adapting/causing others to make proteins that do what you need them to do. Proteins are essentially bio-robots that can manipulate their surrounding by changes in their folds (conformation), for example by exposing binding sites in reaction to something binding to another binding site.

TLDR: nanotech is one of the largest industries in the planet. A lot of promises were made by idiots in the nineties, but biotech, another huge industry, has picked up the slack very well.

I mean... you're surrounded by trillions of perfect nanotech devices. They're called MOSFETs, and they make literally the entire modern world go round.

It is still around, only the buzz around it died

I'm no nanotech scientist, so I won't pretend I know all of the ins and outs here, but I'm sure when most people think about nanotechnology, they're probably picturing something like the later generation iron man suit from the marvel movies made up of billions of tiny nanobots that can reconfigure themselves and such. If such things will ever be possible, they're still a long way off

I have a hunch you probably have some visions in your head of tiny robots similar in size to a red blood cell swimming around in someone's blood stream, that seemed like a trope that was used by a few different sci Fi series when I was growing up, and certainly the kind of thing I personally picture when I think of nanobots. Problem is, at the nano scale, those kinds of things are kind of huge, a blood cell is a few thousand nanometers across. Most of what we're doing with nanotechnology is just a handful of nanometers in size, at the scale of a few molecules or even atoms. Eventually we may be able to put some of those parts together to make tiny robots and computers and such, but right now we're still kind of figuring out how to make the nuts and bolts and gears and such to make those bots out of.

There's also a lot of nanotech research that you may not really think of as technology but more as something like material science or chemistry. Any time you hear about new developments with carbon nanotubes or graphene, that's nanotechnology. Practical applications for stuff like that are still mostly works in progress, we're probably years, decades, maybe even centuries out before some of those things really come into their own, but when we do work out the bugs, they will absolutely be revolutionary.

But it's not all far future stuff, it's almost guaranteed that you have used and maybe even have in your home or on your person right now something that makes use of nanotech in some way. One example I saw mentioned a lot is sunscreen, there's a lot of sunblock that makes use of zinc oxide and/or titanium dioxide nanoparticles, clothing may contain nanoparticles to help with things like waterproofing, reducing odor, etc. there's lots of mundane nanotech that you're probably already taking advantage of.

As a nano engineer, youre 100% right - with the added slowdowns of safety research. Many of these particles are entirely different beasts on a nanoscale, an example commonly used is microscopic copper is just copper, nanoscopic will have you dead within the hour if inhaled (dont quote my timeframe on that one).
That being said many cool materials are still coming out, just aren't yet at that commercialized availability level yet.
For example graphene has the potential to replace copper -at least in high performance applications- cause its got some fucked levels of conductivity
Edit for some more examples cause I'm a nerd about this stuff:
Carbon nanotubes make vantablack, the material that can absorb 99.9% of visible light (not that exciting beyond a party trick commercially, but in areas trying to minimize electromagnetic noise this is revolutionary).
Silver nanoparticles have been shown to have passive disinfectant properties, leading to the possibility of a cloth that you could run dirty water through and make it drinkable.
And my favorite being we've already created the carbon based structures (can't recall if it was nanotubes specifically) with theoretically high enough tensile strength that if made a couple kilometers long could be used to lasso an asteroid and create a space elavator
- So what about APM? That's the thing I'm waiting for :-)