Unlikely as it sounds, a future Apple Watch may be able to identify its owner using nothing more than the heart-rate sensors. In principle, this could allow it to eliminate the need for a PIN (or verification via iPhone unlock) when you put it on in the morning.

The possibility is described in an Apple patent application published today, in which Apple talks of combining a number of different characteristics.

Light emitters and light sensors can be used to perform biometric identification of a user based on identifying characteristics of the user’s vasculature. For example, light information can be obtained at one or more light sensors, and the information can be compared to stored information associated with a user identity. Based on the comparison, the user of the device can be identified as having the user identity.

One example given is measuring the O2 content in the blood. Although current Apple Watches don’t currently act as a pulse oximeter, a teardown found that even the first-generation Watch contains the necessary hardware. It’s been speculated that Apple chose not to activate it in order to avoid the need for FDA approval as a medical device.

The idea of vascular biometrics – also known as vein matching – dates back to the 1980s, and led to commercially available systems in the 1990s, but were mostly superseded by fingerprint readers. Current systems work either on fingers on on the backs of hands.

To identify patterns in hands, near-infrared rays generated from a bank of light emitting diodes (LEDs) penetrate the skin of the back of the hand. Due to the difference in absorbance of blood vessels and other tissues, the reflected near-infrared rays produce an image processing techniques producing an extracted vascular pattern. From the extracted vascular pattern, various feature rich data such as vessel branching points, vessel thickness and branching angles are extracted and stored as a template.

Just yesterday, a study claimed that the Apple Watch is the most accurate wrist wearable for fitness tracking.

Via Apple Insider