I used to work on medical devices - specifically an EEG monitor. One of the things you can do with EEG monitors is an ‘evoked potential’ study. That’s where you shock the patient and see the result in the EEG.
Basically, you are measuring the length of time that the nerves take to conduct the signal from the point of the shock to the patient’s brain. This shows you how screwed up (or not) the nerves in their limb are (the length of time is related to length of limb and to any nerve damage).
I worked on many parts of the system, but I made sure I was one of the people we did the evoked potential study on (I wanted everyone to do it, but not all of the developers would agree).
I’m not sure I could put my finger in a saw, but I sure appreciate that the developer was able to do so. It makes me feel like the thing will actually work.