The recent launch of the iPhone X and its new facial recognition unlocking technology has thrust biometric security back into the popular discourse. A team at the University of Buffalo has now developed a new biometric tool that analyzes the dimensions of your heart to unlock your phone or log you in to your computer.

The old-fashioned password is quickly looking like an ancient relic of the 20th century. Biometric security seems to be the way of the future, with fingerprints, retina scans and facial recognition only the beginning. Practically every conceivable unique biological signature is currently being investigated as a potential form of security.

From a body odor-based ID system, to vein scanning and "brain-prints", your body is full of unique biometric markers that can be harnessed as a personalized passcode. In 2014 a company called Nymi developed a novel, heart-based, biometric system that identifies a person's electrocardiogram signal using a bracelet that can track cardiac rhythms.

Now researchers at the University of Buffalo have taken heart biometrics one step further and developed a system that uses a low-level Doppler radar to identify the unique shape and size of a person's heart.

"No two people with identical hearts have ever been found," says Wenyao Xu, lead author of the new study, who added that people's hearts do not change shape unless they suffer from serious heart disease

The system takes eight seconds to record the unique geometry and rhythm of a person's heart and then it can continuously monitor the person's presence, allowing for continuous authentication without any kind of recurring body contact.

The ability of the system to unobtrusively re-authenticate the user makes the system a little more secure than a regular static, single log-in authentication process. One-time validation systems can easily be compromised, but a system that is continuously authenticating its user is much harder to crack.

The team claims the radar system uses very little power and poses no health risks as it has a signal strength much lower than regular Wi-Fi.

"We are living in a Wi-Fi surrounding environment every day and the new system is as safe as those Wi-Fi devices," says Xu. "The read is about 5 milliwatts, even less than 1 percent of the radiation from our smartphones."

Across a pilot study with 78 subjects, the cardiac scan system achieved an balanced accuracy rate of 98.61 percent and an equal error rate of 4.42 percent.

The team states that further development of the technology will involve a miniaturization of the system to enable it to be installed into computer keyboards or smartphones. The current system also allows for monitoring of an individual up to a distance of 30 meters (98 ft), which the researchers suggest could have uses in airport identification scenarios.

The team is presenting the research in next month at MobiCom, a mobile computing conference in Utah.