The problem with this device (although I applaud the thought of giving the rapist the what-for) is that once its existence is known (i.e. now), rapists will just check for it (possibly in very unsavoury ways) and remove it if necessary.

And unfortunately even barring that, it only works AFTER the penetration has occurred. It doesn't stop rape. It just punishes it.

Sadly I don't think there is an easy way to stop rape.