5. Scanning
Scanning is something that really came to the forefront during the run of the Eleventh Doctor, but it was by far not the first time the screwdriver was used in this manner. But scanning objects can be a complicated process and there are, in fact, multiple methods in which an object can be scanned. Scanning objects to discern their internal nature can be an important function. Knowing the structure of something can help to determine its function and possibly how to disable it, and scanning things is extremely helpful to learn the potential weakness of an enemy or trying to help an ally when they're hurt. Scanning objects to discern their internal structure has become commonplace in the show. The first instances was the Third Doctor in The Sea Devils who scanned the beach for the buried metallic land mines. But how could this function be explained? Is it possible to scan living creatures with sound alone? Most people are familiar with a sonogram that creates a picture of something that is happening within a person's body. Just step this up and you get Acoustic Microscopy, a scanning method that uses non-destructive ultrasound. It penetrates solid material to make the internal structure visible. The Doctor's screwdriver is just being a little more powerful and precise.