Integrated Systems and Photonics, Department of Electrical and Information Engineering, Kiel University, Kaiserstraße 2, 24143 Kiel, Germany.
Nanoscale Magnetic Materials, Department of Material Science, Kiel University, Kaiserstraße 2, 24143 Kiel, Germany.
Sensors (Basel). 2023 May 23;23(11):5012. doi: 10.3390/s23115012.
Magnetoelectric thin-film cantilevers consisting of strain-coupled magnetostrictive and piezoelectric layers are promising candidates for magnetic field measurements in biomedical applications. In this study, we investigate magnetoelectric cantilevers that are electrically excited and operated in a special mechanical mode with resonance frequencies above 500 kHz. In this particular mode, the cantilever bends in the short axis, forming a distinctive U-shape and exhibiting high-quality factors and a promising limit of detection of 70pT/Hz at 10 Hz. Despite this U mode, the sensors show a superimposed mechanical oscillation along the long axis. The induced local mechanical strain in the magnetostrictive layer results in magnetic domain activity. Due to this, the mechanical oscillation may cause additional magnetic noise, deteriorating the limit of detection of such sensors. We compare finite element method simulations with measurements of magnetoelectric cantilevers in order to understand the presence of oscillations. From this, we identify strategies for eliminating the external effects that affect sensor operation. Furthermore, we investigate the influence of different design parameters, in particular the cantilever length, material parameters and the type of clamping, on the amplitude of the undesired superimposed oscillations. We propose design guidelines to minimize the unwanted oscillations.
由应变耦合磁致伸缩和压电层组成的磁电薄膜悬臂梁是生物医学应用中磁场测量的有前途的候选者。在这项研究中，我们研究了电激励的磁电悬臂梁，其在特殊的机械模式下工作，具有高于 500 kHz 的谐振频率。在这种特殊模式下，悬臂梁在短轴方向弯曲，形成独特的 U 形，并具有高的品质因数和有希望的检测极限为 70pT/Hz 在 10 Hz。尽管存在 U 型模式，但传感器仍沿长轴表现出叠加的机械振荡。磁致伸缩层中感应的局部机械应变导致磁畴活动。因此，机械振动可能会导致额外的磁噪声，从而降低此类传感器的检测极限。我们将有限元方法模拟与磁电悬臂梁的测量进行比较，以了解振动的存在。由此，我们确定了消除影响传感器操作的外部影响的策略。此外，我们研究了不同设计参数对不期望的叠加振动幅度的影响，特别是悬臂梁长度、材料参数和夹紧类型。我们提出了设计准则来最小化不需要的振动。
