Just be carefull with that, infections can be nasty.
I would go for a different approach, like a they do with modern car keys. It sends a signal within a certain range, once the car is that range and you grap the handle the car unlocks without you needing to use a real key to unlock it.
Your right about being careful with infection. Thats why im learning more about surgical procedgures. Oh and did you know scientists now have a paper thin battery that runs on the electrolites in our blood. Thats a cool idea for a powersource for this technology.