Project P9: Resonant magnetoelectric sensor systems for the measurement of deep brain stimulation

该项目的目标是制造和研究谐振磁电（ME）传感器和实现三维传感器和传感器阵列，包括模拟信号调理电路。传感器的性能将通过使用真实的人体头部模型的实验以及通过使用脑深部刺激器测量患者的生物磁信号来验证。重点是源自例如脑深部刺激或特定感觉诱发电位的高频（100 Hz以上）、窄带宽（2 Hz以下）周期性信号。为了测量这些高频信号或其谐波，将开发谐振表面微机械传感器，通过真空封装达到高的机械品质因数。传感器的谐振频率通过设计或在操作中通过集成调谐机构调整到特定信号频率。这些MEMS ME传感器将与低噪声放大器和模数转换器混合集成到传感器系统中。使用精密装配技术，将建造3D传感器模块和传感器阵列。对于这些多传感器模块的制造，交换偏置层堆叠作为磁致伸缩组件的研究，不需要外部偏置场。为了测量ME传感器模块的灵敏度、分辨率和方向性，开发并应用了具有三个正交磁场线圈和具有不同电导率区域的真实头部模型的专用测量装置。随后，将在相关的神经医学应用中对本项目沿着的MEMS传感器以及项目P4、P5和P6的适当传感器进行评价。首先，我们测量位于头部模型中的脑起搏器的高频谐波。然后，测量源自患者的脑起搏器的伪影信号，并评估信号重建算法的质量。通过EEG和MEG的同时配准，我们比较了头皮上的信号质量和有效性，并量化了它们之间的相互影响。此外，商业刺激电极的场分布的差异与32个触点不同的布线配置进行了研究。

The project targets on the fabrication and investigation of resonant magnetoelectric (ME) sensors and the realization of 3D-sensors and sensor arrays including analog signal conditioning circuits. The sensor performance will be validated by experiments using a realistic phantom of the human head and by the measurement of biomagnetic signals from patients with deep brain stimulators.The focus is on high frequency (above 100 Hz), narrow bandwidth (less than 2 Hz) periodic signals originating for instance from deep brain stimulation or specific sensory evoked potentials. For the measurement of these high frequency signals or their harmonics resonant surface micromachined ME sensors will be developed which reach high mechanical quality factors by vacuum encapsulation. The resonant frequency of the sensors is adjusted by design or in operation by integrated tuning mechanisms to the specific signal frequency. These MEMS ME sensors will be hybrid-integrated with low-noise amplifiers and analog-digital-converters to sensor systems. Using precision assembly technologies 3D-sensor modules and sensor arrays will be built. For the fabrication of these multi-sensor modules exchange-bias layer stacks as magnetostrictive component are investigated which do not have a need on external bias fields. For the measurement of sensitivity, resolution and directivity of the ME sensor modules a dedicated measurement set-up with three orthogonal magnetic field coils and a realistic head phantom with regions of different electrical conductivities is developed and applied. Subsequently, the MEMS sensors from this project along with suitable sensors from projects P4, P5 and P6 will be evaluated in relevant neuro-medical applications. At first, we measure high frequency harmonics of a brain pacemaker positioned in the head phantom. Then the artefact signal originating from a patient`s brain pace maker is measured and the quality of signal reconstruction algorithms is evaluated. By simultaneous registration of EEG and MEG we compare the signal quality and validity on the scalp and quantify their mutual influence. Further on, the differences in the field distribution of commercial stimulation electrodes with 32 contacts for different wiring configurations are investigated.