面向生物芯片AlN/FeCoSiB复合薄膜的制备及其磁电耦合机理研究

The ultra-sensitivity of magnetoelectric (ME) sensors provides a competitive advantage for the new biochips. The fundamental part of the ME sensor is the ME thin film composite. In this proposal, a ME thin film composite with high ME coefficient at room temperature is prepared for magnetic field detection. FeCoSiB with high permeability, low coercivity and excellent magnetostriction is used as the magnetostrictive component of the thin film composite. AlN with high piezoelectric coefficient and preferred orientation growth is used as the piezoelectric component. The optimal process conditions are discussed in detail, which ensure the prepared the thin film composites have the stable and repeatable properties. The structure of thin film composites is improved through adjusting the substrate/thin films thickness ratio and the ferroelectric/ferromagnetic phases ratio. Then, we will build the magnetic field detection system to detect magnetic particles and discuss the signal-to-noise ratio to further improve the ME properties of the thin film composites. Moreover, considering the magnetostrictive effect, piezoelectric effect, interface strain effect and the interaction between the magnetic particles and thin film composites, we will propose the theoretical models for ME effect of the thin film composites based on the finite element method, equivalent circuit model and field theory. The proposed AlN FeCoSiB thin film composites have the large ME voltage value at room temperature and high sensitivity for magnetic field detection, which are hopeful to decrease the detection limit of the biologic detection and appropriate for the new magnetic biochips.

磁电传感器的高灵敏度为新型生物芯片的开发提供了得天独厚的条件。传感器的核心是磁电复合薄膜，本项目拟选取具有高磁导率、低矫顽力、高压磁系数的FeCoSiB合金为铁磁相，高压电系数、微晶择优取向生长的AlN为压电相，研制室温下具有高磁电系数的复合薄膜。探索复合薄膜的最佳制备工艺，调节衬底薄膜厚度比、两相含量比，优化复合薄膜的结构；搭建磁场检测系统，对磁性颗粒进行检测，分析系统信噪比获得反馈信息，进一步优化复合薄膜的磁电性能；综合磁致伸缩效应、压电效应、界面应变效应、磁性颗粒与薄膜的相互作用，基于有限元、等效电路、场理论等方法建立理论模型，揭示磁性颗粒/复合薄膜相互作用下的磁电耦合机制。本项目研制的AlN/FeCoSiB复合薄膜具有室温下高磁电电压值、对微弱直流磁场灵敏的特点，应用于生物检测有望进一步降低检出限，是研发新型生物芯片的先锋探索工作。

高灵敏磁电传感器应用于生物检测有望进一步降低检出限，为新型生物传感器的开发提供条件，生物芯片的核心是磁电复合薄膜。本项目面向生物芯片，制备了AlN/FeCoSiB和Metglas/PVDF/Metglas磁电复合传感器，探寻了两种复合材料的最佳制备条件，将复合薄膜作为传感器进行了弱磁场探测，在零偏置磁场下复合材料仍然具有磁电耦合效应，最佳偏执磁场和共振频率下传感器的检出限约为3nT。基于Labview，采用锁相放大器、电流源表、波谱分析仪，搭建了磁电信号全自动化检测系统和磁性生物检测平台，采用GPIB通信模式实现全自动化检测。通过两步法成功设计制备了棒状形貌的Fe3O4纳米颗粒代替球形的Fe3O4，并将其用于自制的生物检测系统中进行了磁标签性能的检测。滴加磁性颗粒后传感器输出电压随着颗粒浓度的增加而增加，并出现了超低的检出浓度0.05ng/mL，这与我们之前用球形颗粒进行检测相比提高了一个数量级。在颗粒浓度为0.05 ng/mL-1000 ng/mL的区间范围内，传感器电压输出值随浓度变化具有较宽的线性区间。从磁性标签的弥散场出发理论计算了传感器的检出限，与实验结果吻合较好。反复滴加颗粒，对传感器进行重复性测量，发现传感器具有优良的重复性。.总之，本项目旨在研发室温下具有高磁电电压值、对微弱直流磁场灵敏的磁电复合传感器，应用于生物检测进一步降低检出限。我们通过设计优化磁电复合薄膜和磁性标签，实现了本项目的研究目标，为磁性生物检测系统的开发提供了新的技术、方法与思路。