To measure signals emitted by bio-medical sources like the heart or a skeleton muscle with a high temporal resolution, the generated electrical potentials on the body surface or the generated magnetic flux are usually measured. One big difference between the two measurement types (and the main advantage of the measurement of the magnetic flux) is that the magnetically measured signals are less distorted by surrounding materials of the source compared to their electric counterparts. Unfortunately, the operation of suitable state-of-the-art sensors, which are mainly based on super-conducting quantum interference devices (SQUIDs), is in general very expensive.
Sensors based on the magneto-electric (ME) effect have the potential to be a suitable alternative. During the last years the new ME sensors, developed in collaborative research groups at Kiel University, reached a sensitivity level which makes it possible to detect the human heart beat. Since no cooling is required for this sensor type, the operational cost are relative low. This could lead to an increased number of magnetic measurements for medical diagnostics in the future. In addition the sensors can be placed closer to the measured object and arrays of higher sensor probability can be built up, because the sensors are smaller in size.
The challenging part arises, because these sensors also record mechanical vibrations, whereby the desired signals are superimposed by unwanted signal components. To reduce this coupling effect and increase the usability of such sensors in measurement environments signal processing techniques are applied. Approaches are based on adaptive noise cancellers using non-magnetic noise reference sensors or intelligent sensor read-out schemes.
J. Reermann, E. Elzenheimer and G. Schmidt: Real-time Biomagnetic Signal Processing for Uncooled Magnetometers in Cardiology, IEEE Sensors Journal, January, 2019 (early access, doi: 10.1109/JSEN.2019.2893236)
A. Kittmann, P. Durdaut, S. Zabel, J. Reermann, J. Schmalz, B. Spetzler, D. Meyners, N. X. Sun, J. McCord, M. Gerken, G. Schmidt, M. Höft, R. Knöchel, F. Faupel, E. Quandt: Wide Band Low Noise Love Wave Magnetic Field Sensor System, Sci. Rep., vol. 8, no. 1, pp. 1–10, open access, 2018
J. Reermann, P. Durdaut, S. Salzer, T. Demming, A. Piorra, E. Quandt, N. Frey, M. Höft, and G. Schmidt: Evaluation of Magnetoelectric Sensor Systems for Cardiological Applications, Measurement (Elsevier), ISSN 0263-2241, https://doi.org/10.1016/j.measurement.2017.09.047, 2017
P. Durdaut, J. Reemann, S. Zabel, Ch. Kirchhof, E. Quandt, F. Faupel, G. Schmidt, R. Knöchel, and M. Höft: Modeling and Analysis of Noises Sources for Thin-Film Magnetoekctric Sensors Based on the Delta-E Effect, Proc. DAGA, Kiel, Germany, open access, 2017
P. Durdaut, S. Salzer, J. Reermann, V. Röbisch, J. McCord, D. Meyners, E. Quandt, G. Schmidt, R. Knöchel, and M. Höft: Improved Magnetic Frequency Conversion Approach for Magnetoelectric Sensors, IEEE Sensors Letters, published online, 2017
J. Reermann, C. Bald, P. Durdaut, A.Piorra, D. Meyners, E. Quandt, M. Höft, and G. Schmidt: Adaptive mehrkanalige Geräuschkompensation für magnetoelektrische Sensoren, Proc. DAGA, Kiel, Germany, open access, 2017
P. Durdaut, S. Salzer, J. Reermann, V. Röbisch, P. Hayes, A. Piorra, D. Meyners, E. Quandt, G. Schmidt, R. Knöchel, M. Höft: Thermal-Mechanical Noise in Resonant Thin-Film Magnetoelectric Sensors, IEEE Sensors Journal, published online, 2017
V. Röbisch, S. Salzer, N. O. Urs, J. Reermann, E. Yara, A. Piorra, C. Kirchhof, E. Lage, M. Höft, G. Schmidt, R. Knöchel, J. McCord, E. Quandt, and D. Meyners: Pushing the Detection Limit of Thin Film Magnetoelectric Heterostructures, Journal of Materials Research, published online, 2017
J. Reermann, C. Bald, S. Salzer, P. Durdaut, A. Piorra, D. Meyners, E. Quandt, M. Höft, and G. Schmidt: Comparison of Reference Sensors for Noise Cancellation of Magnetoelectric Sensors, IEEE Sensors 2016, Orlando, November 2016
J. Reermann, S. Zabel, Ch. Kirchhof, E. Quandt, F. Faupel, G. Schmidt: Adaptive Readout Schemes for Thin-Film Magnetoelectric Sensors Based on the delta-E Effect, IEEE Sensors Journal, Volume 16, Number 12, Pages 4891-4900, June 2016
S. Zabel, J. Reermann, S. Fichtner, C. Kirchhof, E. Quandt, B. Wagner, G. Schmidt, and F. Faupel: Multimode Delta-E Effect Magnetic Field Sensors with Adapted Electrodes, Applied Physics Letter, Volume 108, Number 22, 2016
P. Hayes, S. Salzer, J. Reermann, E. Yarar, V. Röbisch, A. Piorra, D. Meyners, M. Höft, R. Knöchel, G. Schmidt, E. Quandt: Electrically Modulated Magnetoelectric Sensors, Applied Physics Letters, Volume 108, Number 18, 2016
J. Reermann, G. Schmidt, I. Teliban, S. Salzer, M. Höft, R. Knöchel, A. Piorra, E. Quandt: Adaptive Acoustic Noise Cancellation for Magnetoelectric Sensors, IEEE Sensors Journal, Volume 15, Number 10, Pages 5804-5812, October 2015
J. Reermann, G. Schmidt, S. Zabel, F. Faupel: Adaptive Multi-mode Combination for Magnetoelectric Sensors Based on the delta-E Effect, Procedia Engineering, Eurosensors 2015, Volume 120, Pages 536-539, September 2015