CHIP SCALE MAGNETIC SENSOR ARRAYS BASED ON MAGNETOVISCOUS EFFECT OF FERROFLUIDS

基于铁磁流体磁粘效应的芯片级磁传感器阵列

• 批准号: 1305653
• 负责人: Srinivas Tadigadapa
• 金额: $ 33万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-05-15 至 2017-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1305653&HistoricalAwards=false
• 关键词: CHIP; SCALE; MAGNETIC; SENSOR; ARRAYS

This project will investigate the design and implementation of a novel magnetometer array capable of picoTesla magnetic field sensitivity at room temperature. The principle of operation of the magnetic sensor is based on the sensitive monitoring of the magnetoviscous effects in ferrofluids using micromachined, shear mode, bulk acoustic wave resonators. The uniqueness is in the exploitation of, hitherto unexplored, response of a ferrofluid atop a high-frequency shear wave resonator to externally applied magnetic field that is sensitively monitored through the at-resonance impedance characteristics of the resonator. Ferrofluids consist of ~10 nm sized ferri- or ferro-magnetic nanoparticles suspended in a carrier liquid. Interaction of the ferrofluid nanoparticles with the surface of the resonator is considered to result in the formation of a dense magnetic double layer at the interface with a high magnetic susceptibility. Application of external magnetic fields results in changes in magnetoviscosity of the magnetic double layer at the resonator-ferrofluid interface and can be accurately monitored using micromachined quartz resonators. High frequency micromachined quartz resonators are highly sensitive to small changes in the viscoelastic loading at the resonator surface and can be used for the quantification of the magnetoviscous effect and is the working principle of the magnetometer proposed here.Intellectual Merit: The proposed work aims at exploring the interaction of high frequency shear waves and magnetic fields on the spontaneous organization of ferromagnetic nanoparticles suspended in a fluid medium focusing specifically on the immediate layers adjacent to the resonator surface. The proposed experiments and model development will attempt to explore the interfacial origins of the phenomenon of magnetoviscosity. Combining real-time viscoelastic measurements with magnetic flux concentrator structures will provide the designs for realizing high-sensitivity magnetic sensors capable of vector measurements of magnetic field and a greater understanding of the magneto-rheological effects. Current experimental techniques on ferrofluids employ shear rates that are five orders of magnitude lower and preclude such interfacial investigations on ferrofluids. This work will demonstrate high-sensitivity, chip-scale, magnetometer arrays capable of resolving pico-Tesla magnetic field vectors.Broader Impact: This project will explore the basic interaction of acoustic waves, magnetic fields, and ferromagnetic nanoparticles in a fluid. A deeper understanding of this phenomenon will provide the tools for understanding the role of thermal energy, dipole interaction energy, and hydrodynamic forces on nanoparticles. This work will elucidate the relationship between the observed rheological properties of the ferrofluids and the agglomeration characteristics of the nanoparticles at ferrofluid-resonator interface. The successful development of the integrated sensors in this proposal has the potential to revolutionize the biomagnetic field detection and imaging. The potential impact of this technology on life science research and functional brain imaging, in particular, is immeasurable because it creates an opportunity to produce an array of portable devices operating at room temperature that are currently unavailable. In addition to supporting graduate student training the proposed work includes the creation of demonstration models using ferrofluids to demonstrate magnetic fields, dipoles and nanoparticle concepts to K-5 students.

该项目将研究新型磁力计阵列的设计和实现，该阵列能够在室温下实现皮特斯拉磁场灵敏度。磁传感器的工作原理是基于使用微机械、剪切模式、体声波谐振器对铁磁流体中的磁粘性效应进行灵敏监测。其独特之处在于利用了迄今为止尚未探索的高频剪切波谐振器顶部的铁磁流体对外部施加磁场的响应，通过谐振器的谐振阻抗特性来灵敏地监测该磁场。铁磁流体由悬浮在载液中的约 10 nm 大小的铁磁或铁磁纳米颗粒组成。铁磁流体纳米颗粒与谐振器表面的相互作用被认为导致在具有高磁化率的界面处形成致密的磁性双层。外部磁场的应用会导致谐振器-铁磁流体界面处磁双层的磁粘度发生变化，并且可以使用微机械石英谐振器进行精确监测。高频微加工石英谐振器对谐振器表面粘弹性载荷的微小变化高度敏感，可用于磁粘效应的量化，这也是本文提出的磁力计的工作原理。 智力优点：本项工作旨在探索高频剪切波和磁场对悬浮在流体介质中的铁磁纳米颗粒的自发组织的相互作用，特别关注与谐振器表面相邻的直接层。所提出的实验和模型开发将尝试探索磁粘性现象的界面起源。将实时粘弹性测量与磁通量集中器结构相结合，将为实现能够进行磁场矢量测量的高灵敏度磁传感器提供设计，并更好地理解磁流变效应。目前的铁磁流体实验技术采用的剪切速率低五个数量级，并且排除了对铁磁流体的此类界面研究。这项工作将展示能够解析皮特斯拉磁场矢量的高灵敏度、芯片级磁力计阵列。更广泛的影响：该项目将探索流体中声波、磁场和铁磁纳米粒子的基本相互作用。对这种现象的更深入的了解将为理解热能、偶极相互作用能和流体动力对纳米颗粒的作用提供工具。这项工作将阐明观察到的铁磁流体的流变特性与铁磁流体-谐振器界面处纳米颗粒的团聚特性之间的关系。该提案中集成传感器的成功开发有可能彻底改变生物磁场检测和成像。这项技术对生命科学研究和功能性脑成像的潜在影响尤其是不可估量的，因为它创造了生产一系列在室温下运行的便携式设备的机会，而这些设备目前尚无法实现。除了支持研究生培训之外，拟议的工作还包括使用铁磁流体创建演示模型，向 K-5 学生演示磁场、偶极子和纳米粒子概念。