How do you design an unforgettable key?

Answer: you change the lock. The idea for this build came to me when I first locked myself out. I had left my key on my desk as walked out, so I needed a key that I could never forget.

THe idea

Press your finger to the sensor, then the door opens.

My Role

It took about two weeks of planning and sketches, then about 1 day for actual implementations. The project is composed of four parts:

• Machining — I designed the profile of the mounting bracket for all of the components that would fit behind the door. It houses an Arduino, a small breadboard, and a mounting bracket for a 12V DC motor. I created a program that would run all of the machining operations to machine the bracket out of aluminum.

• Coding — I wrote the code base for the fingerprint sensor using Adafruit’s Fingerprint library. It can store upwards of 10,000 fingerprints.

• Wiring — I designed the electrical circuit with the intention of having the system plug into a wall socket, so I did not need to worry about having an external battery.

• Installing — I attached the sensor to the outside of the door and attaching the mounting bracket behind the the door handle plate on the inside.

The door is still accessible via a key, but now, I can let people into my room without having to be present.