A new Wee-G sensor-utilizing technology found in mobile phones could be used to detect tunnels underground, as well as oil deposits. The system is designed in a similar fashion to accelerometers in cellphones, known as micro-electromechanical systems (MEM's), used to determine the orientation of the device.
Gravometers are capable of measuring minute changes in the gravitational field of our planet, but current designs are large and expensive, limiting their use.
The gravometer was made more sensitive than typical accelerometers through the use of silicon springs, attached to a sensor just half-an-inch across. Larger devices capable of measuring small local variations in the gravitational field of the Earth have existed for decades. However, this new design is much faster and less expensive than earlier models, which can be the size of a typical car battery and can cost over $100,000.
The Wee-G could be used to find tunnels used by smugglers, used to ferry people and contraband, often across international borders. The devise may also be employed to locate oil deposits without the cost of environmental degradation of drilling.
"There are a lot of potential industrial applications for gravimeters, but their cost and bulkiness have made them impractical in many situations," said Richard Middlemiss of Glasgow University.
The new device is centered on a tiny piece of material weighing a mere 0.0009 grams. This is suspended by a trio of tiny fiber-like strands, acting as an ultra-sensitive spring. As the density of ground beneath the detector changes, the suspended material moves. The shadow of the inner core, cast by light shining on the center, is recorded by detectors, which register the movement.
The significant savings in cost and weight could allow the Wee-G to be fitted to drones, which can take to the skies in the search for tunnels, or deposits of minerals or fossil fuels. Because mineral deposits have a different density than surrounding rock, the Wee-G could easily find veins of precious rocks.
Development of the Wee-G gravometer was detailed in a letter published in the journal Nature.