Sensor systems based on the DeltaE Effect

在SFB855的框架内，研制了一种基于DeltaE效应的新型磁场传感器。它利用悬臂梁的频移，在100 kHz范围内以高频振荡，该悬臂上覆盖有磁致伸缩层，其有效杨氏模数随磁场而变化(DeltaE效应)。该传感器在《自然》杂志上作为研究亮点亮相，允许在低频率下进行宽带磁场测量，一直到直流范围，对微音效应和机械噪声具有很强的抵抗力，并提供完全的设备可积分性。在联合筹备工作中，申请者展示了第一个完全集成的传感器，其中电子读数和机械激励由单一压电层实现。拟议的项目旨在将DeltaE传感器集成到MEMS技术中，并寻求不同的方法来提高其灵敏度。最终目标是在心磁图方面的应用。关于压电谐振器，它旨在利用基于弯曲模式和纵向模式的不同传感器几何形状，这些模式发生在高得多的频率并且提供更好的机械品质因数。必须开发相应的MEMS工艺。为了减小夹持效应，AlN和一种具有较低杨氏模数的改性剂将被用作压电材料。为了使磁电式传感器在磁场中获得机械性能的大变化，人们建立了各种方法。这些方法对DeltaE传感器的适用性将在本项目中进行研究。除了公认的非晶态FeCoBSi合金外，还计划使用非晶态FeGaB合金，由于非晶态FeGaB合金具有较高的矫直力和较大的磁致伸缩，因此对于具有剩余磁场而不是外部偏置磁场的传感器来说，应该是更好的选择。为了更好地了解磁性材料，计划与P2合作对振动悬臂梁进行现场磁光克尔效应测量。用于操作传感器的电子设备将随着传感器的发展而发展。

Within the framework of the SFB 855, a new magnetic field sensor was developed which is based on the DeltaE Effect. It exploits the frequency shift of a cantilever, oscillating at high frequencies in the 100 kHz range, which is coated with a magnetostrictive layer whose effective Youngs modulus changes depending on the magnetic field (DeltaE effect). The sensor, which was presented in Nature as Research Highlight, allows broadband magnetic field measurements at low frequencies down to the DC range, is robust against microphony effects and mechanical noise, and provides full device integrability. In joint preparatory work, the applicants demonstrated a first fully integrated sensor where the electrical readout as well as the mechanical excitation was achieved by a single piezoelectric layer.The proposed project aims at integrating DeltaE sensors into MEMS technology and at pursuing different approaches to enhance their sensitivity. The ultimate aim are applications in magnetocardiography. Concerning the piezoelectric resonators, it is intended to utilize different sensor geometries based on bending modes as well as on longitudinal modes, which occur at substantially higher frequencies and provide better mechanical quality factors. The corresponding MEMS processes have to be developed. AlN and a modification with lower Youngs modulus for the reduction of clamping effects will be used as piezoelectric materials. Various methods are established for magnetoelectric sensors to obtain large changes in mechanical properties in a magnetic field. The applicability of these approaches to DeltaE sensors will be investigated in the present project. In addition to the well approved amorphous FeCoBSi alloys, it is also planned to use amorphous FeGaB alloys, which due to their higher coercivity and larger magnetostriction should be superior for sensors with remanent instead of an external bias field. For a better understanding of the magnetic materials, in situ magneto-optical Kerr effect measurements on the oscillating cantilever are planned in cooperation with P2. The electronics for operating the sensors will be developed along with the sensor development.