[chton]

Today, not very many places. I can imagine a scenario where you want a large group of these to crawl through rubble to find people stuck under it. Most research like this comes with the hope of miniaturizing it enough for medical applications. Imagine this thing, but the size a grain of sand: entering your bloodstream, adapting to whatever task that needs to be done, and when it's finished moving to the stomach to get dissolved. In those applications, using external power makes complete sense, since it's a medical setting anyway, and it provides a great way to keep very fine control.