Athletic, medical uses for new blood pressure band

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Initial prototypes of the “blood pressure watch” with the Empastrap made from piezo-resistive fibres.

ZURICH, SWITZERLAND – A new bracelet designed to make it far easier to take blood pressure readings over time has been unveiled by Empa, the materials science and technology research centre at ETH polytechnic institute in Zurich. It has been working with STBL Medical Research AG to develop “a device that can be worn comfortably on the wrist and records the blood pressure continuously – with no pressure cuff or invasive procedure. The measurement is carried out by several sensors which simultaneously measure the contact pressure, pulse and blood flow on the surface of the skin in the vicinity of the wrist.”

The device will be ready for market after further testing on people and a re-design to streamline the product. Clinical tests are currently underway and Empa says the results are “very promising”.

Blood pressure problems are a leading cause of death worldwide, but fewer than one in two people affected take readings regularly according to the WHO, due to the high cost and inconvenience. Hospital monitoring 24-hour monitoring devices cost about CHF6,000. An additional advantage of a simpler system is the ability to measure blood pressure in a person’s normal setting, rather than a stressful hospital.

The market for the new device therefore should be huge, with more than one billion people needing to measure their blood pressure daily.

Gadgets exist for quick readings, and “60 to 70 million measuring devices are sold annually – however, these do not allow continuous measurement,” says Empa in a statement issued 13 June. “In contrast, constant measurement could provide additional safety margins; in cases where there is a possibility of an imminent heart attack or stroke, the system could give early warning  signals. This is because a heart attack, like a stroke, is preceded by an increased pressure wave, which the system records and analyses. This would enable emergency measures to be taken before anything more serious happened.”

The engineers at Empa, who produced the first prototype four years ago, faced a major hurdle:

“The pressure of the device on the skin changes constantly, meaning that highly sensitive correctional  measurements are necessary. Empa’s Laboratory for High Performance Ceramics sought a suitable solution to this problem within the scope of a CTI project. A sensor made from piezo-resistive fibres in the wristband measures the contact pressure of the device on the skin. Changes in signal strength due to slippage or muscle tension could lead to incorrect measurements. It is these changes that the Empa sensor registers – enabling the measurements to be corrected accordingly. The fibre is electrically conductive, detects any movement or change in pressure, converts this into an electrical signal and transmits this to the measuring device. This enables the measuring accuracy of the ‘blood pressure watch’ to be increased by more than 70 per cent.”

The product will probably be supplied in two versions at the start: a medical monitoring device and a slimmed down version for use by people doing sports, for example.  The pricetag: not a giveaway, but about 10 times less than today’s hospital version.