![](/static/253f0d9b/assets/icons/icon-96x96.png)
![](https://lemmy.world/pictrs/image/0943eca5-c4c2-4d65-acc2-7e220598f99e.png)
I think this might be a “yes, but no” kind of thing.
Yes, these are test strips. Yes, they change color to indicate a reading. Yes, they use chemical reactions to cause that color change.
AFAIK: No, these aren’t for testing blood. No, these don’t seem to be for consumption by an electronic meter. And no, I don’t think this is what OP was asking about.
Like, there’s probably some good info, but not for this thread specifically :P
Source: Pulling it straight out of my ass, but it is informed by my limited experience with medical test equipment, and much less limited experience with electronics.
Is it common? That depends on your context. Since your particular context includes an internet connection, literacy, and living in a situation with the means to reserve space for a child that isn’t home full-time, I feel pretty confident in my estimation that it’s probably not common.
Is it harmful? No. Honestly, I think it’s pretty sweet. My only advice is to not let it stray into forbidden territory, but you seem to already have a pretty good grasp of where the line is.