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

该项目的目标是用新型磁电传感器测量第一批生物磁信号，并以此验证传感器的性能。重点是来自人类心脏、骨骼肌和大脑的低频(低于100赫兹)、宽带(大于20赫兹)信号，这些信号可以通过心磁图(MCG)、磁肌图(MMG)和脑磁图(MEG)进行诊断。为了测量这些信号，可以提高传感器的信噪比，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 MEMS传感器概念，它基于工作在反相模式下的耦合谐振器，保证了高灵敏度和低的声交叉灵敏度。通过在传感器附近集成低噪声放大器，寄生噪声信号的耦合将被抑制。为了降低噪声，还将探索一种改进的频率转换方法，将低频生物磁信号传输到千赫范围内的传感器谐振。首先，本项目中实现的MEMS传感器以及P4、P5和P6项目中的合适传感器将通过测量在人体头部和胸部模体中产生的人工磁信号来表征。为了获得可靠的数据以评估基于ME传感器的心电图的可能应用和诊断意义，将实现一个包括纵隔、胸腔和胸壁等隔室的真实胸腔模型。在下一阶段，计划从大的生物磁信号开始测量ME传感器，从大约100PT的诱发肌肉活动开始。随后，进行生物磁信号强度持续降低的测量。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20PT)，最后是人脑的阿尔法节律(约1PT)。调查的重点将放在周期性信号的测量上，以便通过采样实现高信噪比。

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.