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A sensor that can measure electric field strength

A sensor designed to measure the strength of electric fields has been developed by TU Wien, who claim its creation is smaller, simpler and less prone to distortion than comparable devices.

According to TU Wien, accurate measurements of electric fields is a challenging but vital element for a variety of applications, such as weather forecasting, process control on industrial machinery and high-voltage power lines safety.

TU Wien has developed a silicon-based sensor as a microelectromechanical system. According to TU Wien the device does not distort the electric field it is measuring and therefore, readings are more accurate.

"The equipment currently used to measure electric field strength has some significant downsides," explains Andreas Kainz of TU Wien. "These devices contain parts that become electrically charged. Conductive metallic components can significantly alter the field being measured; an effect that becomes even more pronounced if the device also has to be grounded to provide a reference point for the measurement."

The TU Wien team also say that this type of equipment tends to be difficult to transport. Its new sensor works like so – small, grid-shaped silicon structures are fixed onto a small spring. When the silicon is exposed to an electric field, a force is exerted on the silicon crystals, apparently causing the spring to slightly compress or extend.

An optical solution has been devised to make these small movements visible. This is done through another grid, which is precisely aligned above the movable silicon so the grid openings conceal one another.

The moveable structure moves slightly out of this alignment with the fixed grid, when an electric field is present. This apparently enables light to pass through the openings. According to TU Wien, this light is measured and the strength of the electric field can be determined by an appropriately calibrated device.

TU Wien explains that the sensor doesn’t measure the direction of the electric field, but its strength. It can be used for fields of a relatively low frequency of up to one kilohertz.

"Using our prototype, we have been able to reliably measure weak fields of less than 200 volts per metre," Kainz said. "This means our system is already performing at roughly the same level as existing products, even though it is significantly smaller and much simpler.

"Other methods of measurement are already mature approaches – we are just starting out. In future, it will certainly be possible to achieve even significantly better results with our microelectromechanical sensor.”

Bethan Grylls

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