It would be any medical technology on the order or 10^-6 to 10^-9 meters. For example, by nanoscience and nanotechnology teacher was conducting research to combat cancer. Cancer cells die at a certain temperature, but so will your regular cells. He was trying to find a type of metal that, when exposed to a magnetic field, would heat up into the temperature range that would cook the cancer, but not kill your other cells. Apparently there is already a way to make injections specifically seek out cancer cells. He was going to combine his findings with this cancer-seeking technology to send nanoparticles of that particular metal straight to the cancer, then subject them to a magnetic field via ekg or mri or something (I can’t remember and I’m not well-versed in medical things) so the cancer would die.
He hadn’t yet found a suitable metal for this yet by the time I finished his class, but he implied this technology already exists in certain other countries, but it’s ridiculously expensive to purchase the system, and the manufacturer keeps certain aspects a secret, which is why he’s doing his own research.