Early trials of a smartphone device that monitors blood pressure through a press of the finger have shown promising results.

US researchers have developed a smartphone-based blood pressure monitoring prototype that could one day make measuring the major risk factor for heart attack and stroke more accessible for Australians.

The special phone case uses high-tech 3D printing technology that is embedded with an optical sensor, which measures blood pressure through force applied to an artery in a finger.

It provides a blood pressure reading in the finger in the same way that a blood pressure cuff squeezes an artery in the arm, according to researchers at Michigan State University.

Early trial results, published in journal Science Translational Medicine, showed blood pressure readings were similar using their smartphone device, a standard arm cuff device, and a finger-cuff device used on a group of 30 participants.

About 90 per cent of participants were able to position their finger correctly and get consistent readings after one or two attempts, according to the paper.

Last year the Heart Foundation warned millions of Australians were "ticking time-bombs", unaware they're at risk of a stroke or heart attack because of their dangerously high blood pressure.

Heart Foundation analysis of data from the Australian Bureau of Statistics showed a quarter of adults have high blood pressure that is either untreated or treated inadequately.

This equates to four million people at risk of a heart attack or stroke.

"In Australia, more deaths can be put down to high blood pressure than to any other single risk factor," said Heart Foundation CEO, Adjunct Professor John Kelly.