Quantitative Evaluation for Magnetoelectric Sensor Systems in Biomagnetic Diagnostics

Abstract

Dedicated research is currently being conducted on novel thin film magnetoelectric (ME) sensor concepts for medical applications. These concepts enable a contactless magnetic signal acquisition in the presence of large interference fields such as the magnetic field of the Earth and are operational at room temperature. As more and more different ME sensor concepts are accessible to medical applications, the need for comparative quality metrics significantly arises. For a medical application, both the specification of the sensor itself and the specification of the readout scheme must be considered. Therefore, from a medical user’s perspective, a system consideration is better suited to specific quantitative measures that consider the sensor readout scheme as well. The corresponding sensor system evaluation should be performed in reproducible measurement conditions (e.g., magnetically, electrically and acoustically shielded environment). Within this contribution, an ME sensor system evaluation scheme will be described and discussed. The quantitative measures will be determined exemplarily for two ME sensors: a resonant ME sensor and an electrically modulated ME sensor. In addition, an application-related signal evaluation scheme will be introduced and exemplified for cardiovascular application. The utilized prototype signal is based on a magnetocardiogram (MCG), which was recorded with a superconducting quantum-interference device. As a potential figure of merit for a quantitative signal assessment, an application specific capacity (ASC) is introduced. In conclusion, this contribution highlights metrics for the quantitative characterization of ME sensor systems and their resulting output signals in biomagnetism. Finally, different ASC values and signal-to-noise ratios (SNRs) could be clearly presented for the resonant ME sensor (SNR: −90 dB, ASC: 9.8×10−7 dB Hz) and also the electrically modulated ME sensor (SNR: −11 dB, ASC: 23 dB Hz), showing that the electrically modulated ME sensor is better suited for a possible MCG application under ideal conditions. The presented approach is transferable to other magnetic sensors and applications.

Application of Nomogram Method for the Analysis of Magnetoelectric Interactions in Magnetostrictive–Piezoelectric Composites

“…In addition to determining the ME voltage coefficients for magnetostrictive–piezoelectric structures for the quasi‐static mode and in the region of the longitudinal EMR mode, the nomogram method can also be used to study the ME effect in the microwave region. [ 10 ] Similarly, previously obtained expressions for the microwave region can be used to construct nomograms and further used for their intended purpose.…”

“…[1,2] The parameters of the ME composite can be changed by changing the composition of the magnetic and electric phases, or by changing the orientation of the applied magnetic and electric fields. As a result, a large number of new ME effect-based devices, such as sensors, gyrators, antennas, harvesters, and microwave devices, [3][4][5][6][7][8][9][10][11][12] have been proposed in a wide frequency range. The basis of any ME device is a sensitive element, i.e., an ME composite, and the characteristics of the ME device greatly depend on its parameters.…”

Numerical and Experimental Study of Colored Magnetic Particle Mapping via Magnetoelectric Sensors

“…Several studies have reported the feasibility of a pickup coil as a sensor unit for MPI applications [ 9 , 15 , 16 ]. Magnetoelectric composites have extensive applications as mechanical actuators [ 17 ] and magnetic sensors [ 18 , 19 ] due to high sensitivity and a reasonable limit of detection for medical applications [ 20 ]. A recently developed MPM approach has been introduced by utilizing the ME sensor as a detection unit [ 14 , 21 ].…”

Physics of Composites for Low-Frequency Magnetoelectric Devices

“…The great interest in this device is because, having a simple three-layer Metglas-PMN-PT-Metglas structure, in the near future it can replace a complex electronic device such as a SQUID operating at helium temperature, since comparable values for giant ME voltage coefficient of 4.26 × 10 4 V cm −1 Oe −1 and the equivalent magnetic noise of 2.89 fT Hz −1/2 at EMR frequency on this structure have already been achieved. If we consider its small weight and size parameters and operation at room temperature, then we can expect widespread use of the ME magnetic field sensor in areas such as biomedicine [37][38][39]. Next, we should briefly emphasize the main characteristics of other new ME devices, in which they can compete with well-known serial devices.…”