Electronics Weekly
The result they says is a sensitive detector capable of measuring minute changes in gravity, and at significantly lower cost than a traditional gravity meter (gravimeters).
They believe it could lead to a new type of affordable and portable gravimeters used for volcano monitoring, environmental surveying, and oil exploration.
Gravimeters can be used to measure the gravitational field of the Earth. Specialist meters are used in the oil and gas industry to discover fossil fuel deposits, but the Glasgow researchers believe more widespread use has been limited due to their expense and large physical size.
The Glasgow device, dubbed ‘Wee-g’, uses a commercially available micro-electromechanical systems (MEMS) which are already being used as accelerometers in smartphones.
The big difference is in the sensitivity of the device. While the MEMS technology in phones uses relatively stiff and insensitive springs to maintain the orientation of the screen relative to the Earth, Wee-g employs a silicon spring ten times thinner than a human hair. This allows Wee-g’s 12mm-square sensor to detect very small changes in gravity.
The team used their gravity meter to measure the Earth tides from the basement of the University’s Kelvin building.
Dr Giles Hammond of the University’s School of Physics and Astronomy, one of the co-authors of the paper, said:
“One of the factors which separates gravimeters from simple accelerometers is stability, allowing users to monitor variations in gravity over the course of several days-weeks. We used our Wee-g system to monitor the Earth tides under Glasgow over the course of several days, and our results aligned perfectly with the variations in gravity the model had predicted.”
This demonstrated that a MEMS device can maintain its stability over a long period of time.
The detector, built at the University’s James Watt Nanofabrication Centre, is a collaboration between the School of Physics and Astronomy (Institute for Gravitational Research) and the School of Engineering (Electrical & Nanoscale).
The work is one of the first research outcomes from QuantIC, the UK’s centre of excellence for research, development and innovation in quantum enhanced imaging, which was established in 2015.
Richard Middlemiss, co-author of the paper, said:
“There are a lot of potential industrial applications for gravimeters, but their cost and bulkiness have made them impractical in many situations. Wee-g opens up the possibility of making gravity measurement a much more realistic proposition for all kinds of industries: gravity surveys for geophysical exploration could be carried out with drones instead of planes; and networks of MEMS gravimeters could be places around volcanoes to monitor the intrusion of magma that occurs before an eruption – acting as an early warning system.”
The Glasgow team said they were building industrial partnerships within several sectors to exploit the gravity meter commercially.
The paper, titled ‘Measurement of the Earth tides with a MEMS gravimeter’ is published in Nature.
