New Industry Products

EnOcean Offers STM250 Energy-Harvesting Magnet Sensor

November 03, 2005 by Jeff Shepard

EnOcean GmbH (Oberhaching, Germany), a spin-off from Siemens AG (Germany) and a provider of energy-harvesting wireless technologies, introduced a solar-powered, radio-frequency (RF), magnet-contact sensor that the company claims can eliminate the dependence upon batteries for wireless security systems. According to EnOcean, by doing away with battery monitoring and replacement, the STM250 can operate almost forever without maintenance.

Where a typical wireless security system achieves long life through the use of expensive lithium-ion batteries, STM250 requires only ambient indoor or outdoor light. The amount of light typically available in homes or offices is sufficient to operate the STM250 continuously and store energy for up to six days use. The unit's embedded RF transmitter can send a signal across 300 m outdoors and 30 m indoors through walls; the entire transmission is initiated, undertaken, and completed in approximately 1/1000 of a second.

The STM250 is designed to automatically transmit a signal, using RF protocols, when the contact is opened/closed. A periodic presence signal is sent on the quarter-hour to indicate that the node is operating properly, using stored energy. In a package that measures 109 mm x 17 mm x 16 mm, the STM250 consists of a solar cell energy generator, an energy reservoir, a reed contact switch, a sensor control microprocessor, and a radio transmitter/antenna.

The new radio technology is approved for use in Europe, the United States, and Canada. The STM250 sensors are available in OEM quantities for less than $30 each.