Magnetoelectric Sensors for Frequency Conversion

本项目旨在研究和开发用于脑磁图（MEG）和心磁图（MKG）领域的谐振磁电（ME）传感器。由于共振放大和电流噪声的降低，这些传感器和频率转换方法的利用被认为特别有希望在低频生物磁信号的测量中实现足够低的检测极限。ME传感器将由微纳米系统技术开发，基于多尺度建模获得的结果，包括前端的读出电子器件，用于检测弱生物磁信号，同时将噪声水平降至最低。该项目将在建模（Gerken）、制造（Quandt）和模拟信号处理（Knöchel）之间的密切合作下进行。第一个目标包括音叉传感器的体积微加工和读出电子设备的创建，该电子设备利用频率转换来实现最佳的噪声抑制和最大有用的信号提取。这些努力与噪声特性的理论分析相结合。第二个目标将包括对ME悬臂式传感器的效果增加措施的研究，特别是音叉类型。特殊方面涉及悬臂设计的修改（即通过集成机械应力集中器），磁通量集中器的集成，共振质量因子的增加（即通过真空封装或使用石英作为衬底材料）以及再生系统的应用。作为第三个目标，将研究电磁传感器的电调制。通过体积微加工生产的石英悬臂代替硅悬臂的制造，建模和控制使ME传感器的额外电调制成为可能。其目的是利用偏压场周期性调制基片及其压电系数，通过磁致伸缩引起的磁信号在机械共振频率处产生混合信号，从而增强振荡。如有必要，本项目将使用项目P1和项目P2研究的ME复合材料。ME传感器可作为独立传感器或用于项目P7 - P10的系统集成，以实现相应的目标。

This project is concerned with the research and development of resonant magneto electric (ME) sensors for applications in the fields of magneto encephalography (MEG) and magneto cardiography (MKG). The utilization of these sensors and a frequency conversion method are considered especially promising for achieving a sufficiently low limit of detection in the measurement of low frequency bio magnetic signals, due to resonance amplification and reduction in current noise. ME sensors are to be developed by micro- and nanosystems technology, based on results obtained by multiscale modelling including the readout electronics for front-ends, for the detection of weak bio-magnetic signals while minimizing the noise level. The project will be conducted in close collabora-tion between modelling (Gerken), fabrication (Quandt) and analog signal processing (Knöchel). The first goal comprises volume micromachining of tuning fork sensors and creation of readout electronics which make use of frequency conversion to enable optimum noise suppression and maximum useful signal extraction. These efforts are combined with a theoretical analysis of the noise properties. The second goal will consist of investigation of effect increasing measures for ME cantilever sensors, specifically of tuning fork type. Special aspects concern modifications in the design of the cantilevers (i.e. by integrating mechanical stress concentrators), the integration of magnetic flux concentrators, an increase of the quality factor in resonance (i.e. by vacuum packaging or by using quartz as substrate material) as well as the application of regenerative systems. As a third goal electrical modulation of the ME sensors will be investigated. Fabrication, modelling and control of quartz instead of silicon cantilevers produced by volume micromachining enable an additional electrical modulation of the ME sensors. The aim is to periodically modulate the substrate and its piezoelectric coefficient by an electrical bias field, whereby the magnetic signal caused by magnetostriction causes mixed signals at the mechanical resonance frequency, which enhance the oscillation. If necessary, this project will use the ME composites investigated by projects P1 and P2. The ME sensors will be available as standalone sensors or for system integration by projects P7 - P10 for achieving their corresponding goals.