Scientists have developed a new watch-like device that can be worn comfortably on the wrist and records blood pressure continuously - with no pressure cuff or invasive procedure.
The device measures blood pressure through several sensors which simultaneously measure the contact pressure, pulse and blood flow on the surface of the skin in the vicinity of the wrist.
"This measuring device can be used for medical purposes, for example as a precaution for high-risk patients or for treating high blood pressure, but also as a blood pressure and heart rate monitor for leisure activities and sports as well as for monitoring fitness in high-level sports," said Michael Tschudin, co-founder of the company STBL Medical Research AG (STBL) in Freienbach, Switzerland which developed the device.
Measuring and monitoring blood pressure is a tedious business for patients. It usually involves a cuff which is activated every 15 minutes over several hours and compresses the upper arm, a cumbersome measuring device on the body, or in some cases even invasive monitoring, in which a catheter is inserted into the artery.
The device would offer a more pleasant method for measuring blood pressure.
The researchers had to overcome one particular obstacle in the new technology: 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 found a solution. 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.
Clinical trials of the device are currently under way. The first measurements have already been taken in parallel with a catheter procedure - with very promising results.
The product should initially be supplied in two versions: a medical monitoring device and a "slimmed down" version for leisure use by sportsmen and women and ordinary people.
"The sensor will be cheaper than existing 24-hour monitoring devices, such as those currently used in hospitals," said Tschudin.