Magic sensor. Dr Gerd Scholl behind a tyre fitted with an autonomous sensor (yellow). This long- lived sensor is powered solely by the changes in pressure it measures, requiring no battery. It is only active when there is a change to measure. Voltage is generated in its piezoelectric materials by changes in pressure. The voltage is converted into a radio signal transmitted by an antenna. This data can be picked up by a receiver up to 20 metres away. Scholl is one of the team from Siemens, Germany, that developed the sensor. This sensor is being co-developed with Continental to check tyre pressure while driving.