Watching an MVA session on What’s new in Windows 8.1 Security, from the fourth module (with Nelly Porter) I learnt that if someone were to cut my finger and try gaining access to my iPhone 5S via the fingerprint sensor that will not work! That’s because the iPhone 5S (and above) fingerprint reader is a capacitive sensor and requires a “live” finger than a dead one. (I guess it’s similar to capacitive vs resistive touch screens. The former require you to touch the screen with a body part because it makes use of the body electricity to register the touch). Nice!
The other type of fingerprint scanners are optical sensors. These are high-res and used by Governments at border control etc. The chopped finger might work there, I don’t know …