Frequency-modulated magnetoelectric sensor systems for the measurement of broadband, low-frequency biomagnetic fields

该项目的目标是用新的磁电传感器测量第一个生物磁信号，并验证传感器的性能。重点是低频（低于100 Hz），宽带（超过20 Hz）的信号，来自人类心脏，骨骼肌和大脑，可用于诊断心磁图（MCG），磁肌描记术（MMG）和脑磁图（MEG）。为了测量这些信号，将提高传感器的信噪比，并降低交叉灵敏度。为此，我们提出并研究了新的表面微机械MEMS ME传感器的概念，这是基于耦合谐振器工作在反相模式，承诺高灵敏度和低的声学交叉灵敏度。通过在传感器附近集成低噪声放大器，将抑制寄生噪声信号的耦合。为了降低噪声，还将探索一种改进的频率转换方法，该方法将低频生物磁信号转换为kHz范围内的传感器谐振。首先，本项目中实现的MEMS传感器与项目P4、P5和P6中的合适传感器一起沿着，将通过测量人体头部和胸部幻象中产生的人工磁信号来表征。为了获得可靠的数据来评估可能的应用和基于MCG的ME传感器的诊断意义，将实现包括纵隔、胸膜腔和胸壁等隔室的真实胸部模型。在下一阶段，计划对先证者进行ME传感器测量，从大约100 pT的诱发肌肉活动的大生物磁信号开始。随后，进行连续降低的生物磁信号强度的测量。这包括触发的心脏信号，来自自发活动的骨骼肌和眼肌的信号（约100）。20 pT），最后是人类大脑的阿尔法节律（约20 pT）。1 pT）。调查的重点将是周期性信号的测量，以实现高的信号-噪声比的采样。

The objective of the project is to measure with new magnetoelectric sensors first biomagnetic signals and therewith validate the performance of the sensors. The focus is on low-frequency (below 100 Hz), wide-band (more than 20 Hz) signals originating from the human heart, the skeletal muscle and the brain, which can be utilized diagnostically by magnetocardiography (MCG), magnetomyography (MMG) and magnetoencephalography (MEG). To measure these signals the signal-to-noise ratio of the sensors will be improved and the cross-sensitivity will be reduced. For this purpose we propose and investigate new surface micromachined MEMS ME sensor concepts which are based on coupled resonators operated in anti-phase mode which promise high sensitivity and low acoustic cross-sensitivity. With the integration of a low-noise amplifier close to the sensor the coupling of parasitic noise signals will be suppressed. For the noise reduction also a modified frequency-conversion approach will be explored which transfers the low-frequency biomagnetic signals to the sensor resonance in the kHz-range.At first, the MEMS sensors realized in this project along with suitable sensors from projects P4, P5 and P6 will be characterized by measuring artificial magnetic signals generated in phantoms of the human head and chest. In order to acquire reliable data for evaluating possible applications and the diagnostic significance of ME sensor based MCG a realistic thorax model including compartments like mediastinum, pleural cavity and thoracic wall will be realized.In the next phase, ME sensor measurements with probands are planned, starting with large biomagnetic signals, as from evoked muscle activities at about 100 pT. Subsequently, measurements of continuously reduced biomagnetic signal strength are conducted. This includes triggered heart signals, signals from spontaneously active skeletal and eye muscles (ca. 20 pT) and finally the alpha rhythms of the human brain (ca. 1 pT). The focus of the investigations will be on the measurement of periodic signals in order to achieve a high signal-to-noise ratio by sampling.