Self-powered appliances - no batteries needed

Appliances that need no cables or batteries but operate purely on power generated from their surrounding vibrations could save manufacturers and consumers large sums of money, according to scientists at the University of Southampton.

Professor Neil White and his colleagues at the University's Department of Electronics and Computer Science realised three years ago that sensors were being used in increasingly diverse application areas where physical connections to the outside world were difficult. For example, if a sensor was embedded within a structure or appliance, routine maintenance such as changing batteries could cause significant problems and cost time and money in terms of downtime.

Professor White and his team set out to explore the possibility of a self-powered sensor. They explored two devices: a magnet and coil arrangement where relative movement between the coil and the poles of a permanent magnet generates electricity by electromagnetic induction; and a second device based on piezo-electric material to generate electrical energy from vibration-induced deformations. They adopted the former device in the development of their system. The power generated by the sensor is based on its vibrations, so they needed to find applications that vibrate in order to test its effectiveness.

"We initially thought of road bridges," comments Professor White, "but modern-day bridges don't shake that well, apart from the Millennium bridge that is! This will work best if you have a sensor buried in a device that you cannot easily access. The ideal scenario is to have a device that will generate power from a vibration source which will in turn power the sensor."

The team has tested the sensor on several applications. Having assessed car floors, jack-hammers and motor cycle handlebars, they have found that helicopter rotor blades and fitness cycle machines might also be suitable applications.

"A self-powered sensor could be used to power additional features on equipment," comments Professor White. "For example, on a fitness cycle machine, the power generated could power the display panel. The big advantage is that it would reduce the need for batteries, cabling and downtime."