If you don’t want to carry keycard or memorize a passcode, this build from Electronoobs might be just the thing.
The system uses a fingerprint reader to check to see if you have access, and if approved, the device’s Arduino Mega unlocks the theoretical door using a micro servo motor. Three push buttons and a 16×2 LCD screen complete the user interface, and allow more authorized fingers to be added with the main person/finger’s permission.
While you might question the security gained by a hobby servo, the video notes that this could trigger any sort of security device, perhaps via a relay or electromagnetic coil lock. Besides security, the build gives a good introduction to Arduino fingerprint scanning, as well as the use of an SD card for data logging functions.
[original story: Arduino Blog]