72.4 MB (7.3 MB compressed)
5879 x 4303 pixels
49.8 x 36.3 cm ⏐ 19.6 x 14.3 in (300dpi)
VOLKER STEGER / SIEMENS / SCIENCE PHOTO LIBRARY VOLKER STEGER / SIEMENS / SCIENCE PHOTO LIBRARY
Magic sensor. Technician monitoring an autonomous sensor on a candle. This long-lived sensor is powered solely by the changes in temperature it measures, requiring no battery. It is only active when there is a change to measure. Here, it is acting as a safety device. Voltage is generated in its pyroelectric materials by changes in tempera- ture. 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. Similar sensors can be used to continuously check the pressure of vehicle tyres. The sensor was developed by Siemens, Munich-Perlach, Germany.
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