The Walabot DIY Wall Scanner is essentially a glorified stud finder for Android phones. I've seen several online advertisements for it and I've been curious, but I wasn't willing to fork over $100 to find out. The price recently dropped from $100 to $50 and a couple of people in my company asked about it, so I ordered one to test it out. I made a video showing how it works, check it out: https://youtu.be/mxV3sofJm4s
I don't have any concrete at my home to test it on, but it worked pretty well on drywall. Not amazing, but pretty good. If you're only after a stud finder, I recommend buying a stud finder. That's a lot faster. Or you could just do what these people did and drill a million holes in your ceiling.
Haha, just kidding, don't do that.
If you have a need for the other features on this device, such as finding water lines and electrical wiring, it's a pretty cool tool. You can find the Walabot online here: https://walabot.com/diy