Scientists at TU Vienna develop tiny electric field sensor
An electric field sensor based on silicon

Scientists at TU Vienna develop tiny electric field sensor

Researchers at the Technology University of Vienna have developed a sensor capable of measuring electric fields that is a fraction of the size of comparable devices. 

The ability to measure electric fields with accuracy is vital for industrial applications in manufacturing, weather forecasting and the maintenance of electricity infrastructure.

Now, researchers at the Technology University of Vienna (TU Wien) have developed a silicon-based sensor that acts as a microelectromechanical system. Unlike many conventional measuring devices currently in use, it is able to measure electric fields without distorting them.

The device has been developed with the help of the Department for Integrated Sensor Systems at Danube University Krems. A paper detailing the new concept has been published in the electronics journal Nature Electronics.

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Measuring electric fields without distortion

Current methods for measuring electric fields can be inaccurate and clunky. “The equipment currently used to measure electric field strength has some significant downsides,” said Andreas Kainz from the Institute of Sensor and Actuator Systems at TU Wein.

“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.”

Another drawback is size. Traditional equipment tends to be both impractical and difficult to take from one place to another. The TU Wein alternative appears to counter both of those issues.

Being made from silicon avoids interfering with the field it’s attempting to measure. Its small size makes it easy to transport, tiny enough to fit into wearables and promises to simplify the measuring process.

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Silicon structures

The device works by utilizing small, grid-shaped silicon structures that are just a few micrometres in diameter. These are fixed onto a small spring. When the silicon is exposed to an electric field, a force is exerted on the silicon crystals, causing the spring to compress or extend.

Another grid – this one fixed – is located above the silicon grid and is lined up with such precision that the grid openings on one grid are entirely covered by the other. So, if an electric field is present, the silicon grid will move out of alignment and cause light to pass through the gaps.

The strength of the electric field is calculated from the amount of light escaping by using “an appropriate calibrated device”.

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Tiny silicon sensor brings precision

The new silicon sensor is designed to measure the strength of an electric field rather than its direction. It’s precise enough to measure 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,” said Kainz. “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,” he said, “it will certainly be possible to achieve even significantly better results with our microelectromechanical sensor.”