A POSITION-finding device that uses the Earth’s magnetic field could take over from GPS when no satellites are in view.
Because the angles at which magnetic field lines intersect the Earth’s surface are different at every point on the planet, they can be used for location. Previous magnetic sensors were too large to carry by hand and needed liquid nitrogen to keep cool, but now researchers at Virginia Tech in Blacksburg have created a device just 10 centimetres across ().
At its heart is a piezoelectric layer (PZT) stuck to a material…
