A smartphone that can take the pulse of a user just by looking at his or her face was unveiled in Japan on Monday.

Technology giant Fujitsu plans to put the invention to practical use within a year, enabling people at work or at home to track their health and collect data for analysis without wearing special devices.

The smartphone works by measuring variations in the brightness of a person's face caused by the flow of blood.

Researchers say countless tiny blood vessels run through the face, enabling monitoring of haemoglobin which absorbs green light. Haemoglobin is a protein found in red blood cells that contains iron and transports oxygen.

Simply pointing a camera at a person's face for as little as five seconds will enable pulse-taking, while the technology automatically filters out the effect of head movements or changes caused by standing up quickly.

"Even at a busy workplace, or any time a person is sitting in front of a PC, whether for teleconferencing or writing e-mails, their pulse can be measured during brief moments of quiet," the company said in a press release.

"At home, a camera built into a TV can measure the pulse of people relaxing in front of it, or a mirror, for when people are getting ready in the morning," it said.

"Pulse detectors built into gates at event sites or control points at airports could be a possible security application by detecting people in ill health and people acting suspiciously."