In biometrics, 3D devices focus on unique physical characteristics. For example, studies suggest that your ear has a shape as unique as your fingerprint which can be used to identify you. 3D facial scans are also common and may prove to be more accurate than 2D facial scans.

Generally, 3D biometric sensors are less available than 2D sensors and there are not as many standardized specifications from which to compare 3D sensors, because this technology is still in development.

Two and three dimensional sensor technologies are often combined for systems which recognize both 2D and 3D imagery.

This is the case with a European bank which, in 2006, added a facial recognition to increase security. However, there are not many, off-the-shelf alternatives available.

When shopping for a biometric lock, whether it is 2D or 3D, pay attention to certain specifications:

* Dots Per Inch (DPI)—indicates image resolution; look for a DPI of 400 or more

* False Acceptance Ratio (FAR)—the likelihood of a match being made incorrectly

* False Rejection Ratio (FRR)—the likelihood of a true match being rejected