New high-sensitivity hybrid magnetostrictive/electroactive magnetic field sensors

A recently developed class of magnetic field sensors is based on the action of a magnetostrictive material on a piezoelectric material. Described here is a significant improvement on this class, a passive magnetic field sensor made of layers of Terfenol-D {Fe2(Dy0.7Tb0.3)} magnetostrictive material and ceramic PZT-5. These devices show a large magnetic field sensitivity of order 6 kV/T. Application of this device to harvesting vibration energy indicates that more than 10 mW of electrical power can be harvested using a Terfenol-D/PZT/ Terfenol-D sandwich (volume = 1 cm3) from 30 Hz vibrations having an acceleration of 0.5 g.