Lightweight battery sticks up for patients

Ultra-lightweight battery technology has been used to create wire-free medical sensors that are as easy to use as a sticking plaster, their German developers claim. The plasters monitor pulse, temperature, respiration and blood pressure.

The Fraunhofer Institute for Integrated Circuits said a new system called Body Area Network (BAN) will offer patients comfort and convenience while giving doctors access to the data they need 24 hours a day.

BAN integrates a medical sensor, microprocessor and miniature RF antennae on to a flexible substrate that can be attached to the body in the same way as an adhesive dressing.

The system is the first to be powered by foil battery technology developed by the Fraunhofer Institute during research into ultra-lightweight energy sources. The foil battery uses solid rather than liquid electrolytes, because the latter are toxic and need to be surrounded by a solid casing. This makes the batteries too cumbersome to be worn next to the body for long periods.

The foil battery is made from a paste composed of polymer electrode or electrolyte material, sealed in a metallic foil to create a flexible power cell less than 1mm thick.

According to Fraunhofer, the battery could power one BAN plaster for 24 hours. Because the materials are relatively easy to process, it said production costs should be low enough to make each device disposable.

The data they collect is transmitted by RF to a central processing unit no bigger than a mobile phone, which then sends it to the wearer’s doctors via GSM connection or the internet.

BAN is designed to be used in hospitals and at home by high-risk patients who need continual monitoring.

‘The key is ease of use and comfort,’ said Hans-Joachim Moersdorf, an engineer working on BAN. ‘When the power runs out patients will be able to throw the device away and put on a new one,’ he added.

The Institute hopes the battery technology will eventually appear in a wide range of disposable products where a temporary power source is needed, such as smartcards and security tags.