Sensor systems based on the DeltaE Effect

在sfb855的框架内，开发了一种基于德尔塔效应的新型磁场传感器。它利用悬臂梁的频移，在100 kHz范围内的高频振荡，其表面涂有磁致伸缩层，其有效杨氏模量随磁场变化（DeltaE效应）。该传感器在《自然》杂志上发表，作为研究亮点，它允许在低频到直流范围内进行宽带磁场测量，对麦克风效应和机械噪声具有很强的抗扰性，并提供完整的设备可集成性。在联合准备工作中，申请人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是由单个压电层实现的。该项目旨在将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。最终目标是在心脏磁图上的应用。关于压电谐振器，打算利用基于弯曲模式和纵向模式的不同传感器几何形状，它们发生在更高的频率上，并提供更好的机械质量因素。必须开发相应的MEMS工艺。为了减少夹紧效应，AlN和具有较低杨氏模量的改性将被用作压电材料。为了获得磁场中机械性能的大变化，建立了各种磁电传感器的方法。这些方法对DeltaE传感器的适用性将在本项目中进行研究。除了已被广泛认可的非晶态FeCoBSi合金外，还计划使用非晶态FeGaB合金，由于其具有更高的矫顽力和更大的磁致伸缩，对于残余而不是外部偏置场的传感器来说，它应该是优越的。为了更好地了解磁性材料，计划与P2合作对振荡悬臂进行原位磁光克尔效应测量。操作传感器的电子器件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.