[wordtothedevice]

"Formal methods" of verification for medical devices usually means writing detailed product requirements in prose that are traced to manual test cases. Unit test coverage on all the software I worked on was pretty low, and I never heard of anyone using formal program verification, but there were armies of manual testers that found way more bugs than any automated tests did anyway.

Source: I worked on anesthesia machines, cath lab equipment, and patient monitoring devices at big companies in the US.