Piezo-resistive fibers enable "blood pressure watch" with continuous monitoring
By Darren Quick
June 13, 2013
Blood pressure is one of the main vital signs, measuring the pressure of the blood upon the walls of blood vessels as it is pumped around the body by the heart. High blood pressure, or hypertension, places increased stress on the heart and can be an indicator of other potentially fatal health problems, such as stroke, heart attack, and heart failure. Most people will have had their blood pressure tested using a sphygmomanometer on a visit to the doctor, but a new wristband device is set to provide a more convenient and continuous way to keep a watch for signs of trouble.
Developed by Switzerland-based company STBL Medical Research AG, the new “blood pressure watch” relies on a wristband made from piezo-resistive fibers developed at the Swiss Federal Laboratories for Materials Science and Technology (EMPA). These fibers measure the contact pressure of the device on the skin to overcome the problem of the device slipping on the wrist or muscle tension that can affect the measurements.
Being electrically conductive, the fibers are able to detect any movement or change in pressure, which EMPA says enables the device to correct for any changes in signal strength and increase the accuracy of the sensor by more than 70 percent. This allows for continuous blood pressure monitoring without the use of the arm-numbing pressure cuffs used by sphygmomanometers.
With cardiovascular diseases being the most common cause of death worldwide, EMPA says there are around 60 to 70 million blood pressure measuring devices sold annually. However, these do not offer continuous monitoring in the patient’s natural environment. Ticking both these boxes, the device has the potential to detect the early warning signs of a stroke or heart attack and alert the wearer so they could take action before serious damage is done.
The device is currently undergoing clinical trials, which have seen measurements taken in parallel with an invasive arterial catheter system that also allows continuous monitoring. The researchers say the results thus far have been “very promising.” The device will be much cheaper than such measuring methods, with the team claiming the blood pressure watch will be around ten times cheaper than existing 24-hour monitoring devices used in hospitals that can cost up to 6,000 Swiss francs (approximately US$6,500).
In addition to a medical monitoring device, the team also plans to release a “slimmed down” model aimed at the sports market.