A DIY Maker by the name of Grant Gibson has designed a biometric security box, or more simply, a lockable toy box with fingerprint access used to store his son’s toy car collection.
The heart of the system? An Atmel-powered Arduino Uno (ATmega328) and Optical Fingerprint Sensor from Adafruit. As can be seen in the video below, the electronics are all housed in the lid of the box, neatly protected by a sheet of 2mm clear acrylic.
“The box uses a standard hobby servo as the latch to lock and unlock the lid based on the fingerprint detector. Fingerprints are initially registered directly into the Flash memory of the fingerprint scanner using the free SFG Demo software on a Windows PC,” Gibson explained in a recent blog post.
“In order to give the box a battery life measured in months or years rather than hours, I used a Pololu SV power switch (I got mine from Proto-Pic) between the battery pack and the Arduino. This switch allows a standard hardware button to power the Arduino on and off. But more importantly, a separate logic input on the Pololu allows the Arduino to turn itself off automatically after a predefined timeout in the script.”
According to Gibson, the locking mechanism is simple but effective: a notch carved out of the standard servo horn hooks round a screw mounted inside the box base.
“The servo ‘locks’ at approximately 90 degrees, at which point it is tightly wrapped around the screw. Because the screw head is chamfered, the servo horn gets a really tight grip, pulling the box lid down hard against the base,” he continued. “And because the servo horn is pointing straight down at 90 degrees the box stays ‘locked’ shut even when the servo is turned off.”
Interested in learning more about Grant Gibson’s biometric security project? You can check out his official page here.