I am busy wrapping the Nurugo SDK for @Leonidas Brasileiro. It uses a very simple device that attaches to your mobile to "mirror" your fingerprint to the camera. No power required and no USB connections required. It uses your device's camera and flash/torch to capture the fingerprints. The raw fingerprint data can be stored and used for comparing scanned fingerprints with what you have stored in your database. I am only doing the wrapper for scanning of the fingerprints and returning data from the lib to B4A and not implementation of a database - that is up to the B4A user to design his/her own app.