Inorganic Functional Materials

M.Sc. Viktor Schell

Research

Kaiserstraße 2, R. A-207
Phone: +49 431 880-6224
Telefax: +49 431 880-6203
visc@tf.uni-kiel.de

Details

Research

Surface Acoustic Wave Magnetic Field Sensors

In Germany, diseases of the circulatory system are the most common cause of death. Heart diseases made up 30 percent of all fatalities in the year 2015, while eight percent died from diseases of the brain. Therefore, a good understanding and an early diagnosis of these life-threatening conditions is necessary. Since they are non-invasive and comparatively simple, electrocardiography (ECG) and electroencephalography (EEG) are the most common clinical diagnostic methods for the measurement of heart- and brain signals. The disadvantage of these methods lies in the need of constant body contact of the electrodes, which makes long-term monitoring difficult. An alternative is the measurement of the magnetic fields of the electron and ion currents in the human body by means of magnetocardiography (MCG) and magnetoencephalography (MEG). Direct body contact is not necessary in these methods and additionally the human body is transparent to magnetic fields, in contrast to electric fields, whose amplitude highly depend on the penetrated tissue. However, the strength of these magnetic fields lies in the range of pico- to femtotesla at frequencies of 1 to 1000 Hz and therefore several orders of magnitude below the earth’s magnetic field. The Collaborative Research Centre (CRC) 1261 is aiming towards the development of non-cooled and unshielded biomagnetic interfaces for the measurement of heart and brain magnetic fields. Those interfaces are sensors based on magnetoelectric thin film composites.

An alternative sensor concept are surface acoustic wave (SAW) magnetic field sensors, especially those using Love waves. SAW sensors use the inverse piezoelectric effect to generate high frequency acoustic waves on piezoelectric substrates. A change in wave velocity can be induced by an external factor depending on the field of application e.g. by gases, temperature, pressure, humidity, biological molecules or magnetic fields. Thus, the change of velocity can be used for the measurement of the specific quantity. For the measurement of magnetic fields the velocity change is based on the ΔE effect, i.e. the change of Young’s or the shear modulus with magnetization of a mangetostrictive material. Employing a guiding layer confines the acoustic wave at the surface of the sensor resulting in higher sensitivities in the case of shear horizontal waves. These horizontal shear SAWs are termed Love waves.

Love wave magnetic field sensors are characterized by a large bandwidth (~1 MHz), large dynamic field range (~100 dB) and a low limit of detection (70 to 25 pT/Hz1/2 at 10 to 100 Hz) and are therefore promising candidates for the aspired biomagnetic applications.

Publications

  • Schell, V.; Müller, C.; Durdaut, P.; Kittmann, A.; Thormählen, L.; Lofink, F.; Meyners, D.; Höft, M.; McCord, J.; Quandt, E. (2020). Magnetic anisotropy controlled FeCoSiB thin films for surface acoustic wave magnetic field sensors. Applied Physics Letters, 116, 073503. doi: 10.1063/1.5140562

 

  • Hayes, P.; Jovičević Klug, M.; Toxværd, S.; Durdaut, P.; Schell, V.; Teplyuk, A.; Burdin, D.; Winkler, A.; Weser, R.; Fetisov, Y.; Höft, M.; Knöchel, R.; McCord, J.; Quandt, E. (2019). Converse Magnetoelectric Composite Resonator for Sensing Small Magnetic Fields. Scientific Reports, 9(1), 16355. doi: 10.1038/s41598-019-52657-w

 

  • Labrenz, J.; Bahr, A.; Durdaut, P.; Hoft, M.; Kittmann, A.; Schell, V.; Quandt, E. (2019). Frequency Response of SAW Delay Line Magnetic Field/Current Sensor. IEEE Sensors Letters, 1–1. doi: 10.1109/LSENS.2019.2943129

 

  • Hayes, P.; Schell, V.; Salzer, S.; Burdin, D.; Yarar, E.; Piorra, A.; Knöchel, R.; Fetisov, Y. K.; Quandt, E. (2018). Electrically modulated magnetoelectric AlN/FeCoSiB film composites for DC magnetic field sensing. Journal of Physics D: Applied Physics, 51(35), 354002. doi: 10.1088/1361-6463/aad456

 

Conference Talks

  • V. Schell, C. Müller, P. Durdaut, M. Yalaz, A. Kittmann, M. Höft, J. McCord and E. Quandt, Love Wave Magnetic Field Sensors - Fabrication, Characterization, Application in 2019 MRS Fall Meeting & Exhibit, Boston, USA, December 1st - 6th, 2019.

 

  • V. Schell, P. Durdaut, C. Müller, A. Kittmann, J. McCord, M. Höft and E. Quandt, Substrate Materials for High Sensitivity Magnetic Field Sensors in 4th Euro Intelligent Materials 2019, Kiel, Germany, June 17th - 19th, 2019.

 

Search