Chair for Multicomponent Materials

Magnetoelectric magnetic field sensors

Our work on magnetoelectric field sensors has been carried our within the framework of the Collaborative Research Center SFB 1261 "biomagnetic sensing".


In recent years, interest in magnetoelectric (ME) composites has increased very strongly. In addition to applications in the field of energy harvesting and other areas, ME composites turned out to be very attractive for the detection of very low AC magnetic fields. Single-phase ME materials exhibit only extremely small magnetoelectric coefficients αME = δEH and do not lend themselves to magnetic field sensors. Huge ME coefficients can be obtained with composite materials where the ME effect is a product property (see Fig.1). Here the strain of a magnetostrictive material in a magnetic field is transferred to a piezoelectric material via elastic coupling and can be measured as a voltage. With this composite approach, both the magnetostrictive and the piezoelectric components can be optimized independently. While bulk composites have been investigated for many years, our joint research with other groups in Kiel focuses on fully integrable thin film composites.


Fig. 1 Sketch of an ME sensor where the magnetostrictive and piezoelectric layers are deposited on a Si cantilever.

High ME coefficients are generally obtained by taking advantage of the mechanical resonance of a ME sensor on a vibrating cantilever. Depending on the quality factor Q of the resonator, amplifications of more than three orders of magnitude can be achieved. For the measurement of very low-frequency signals for medical applications this, however, causes two problems. On the one hand, the resonance frequencies of the current sensors are far above the relevant frequency range, and on the other hand, a high Q factor gives rise to a very narrow bandwidth.


The activities of the Chair for Multicomponent materials in magnetoelectric magnetic field sensors include the following subjects:

Delta E effect sensors

Novel sensor concepts

Magnetic particle imaging with magnetoelectric sensors