Characterization of Microstructure and Composition of Magnetostrictive Nanobars for Bio-sensor Application
EMSL Project ID
18401
Abstract
As an important type of sensor platforms, acoustic wave (AW) devices have been attracting considerable attention since they provide a high sensitivity with a real-time detection capability. In most of these applications, the AW devices actually serve as a mass detector. That is, AW devices are operated based on the principle that the resonance frequency shift with the mass load attached on the device. Therefore, there are two critical parameters, mass sensitivity (Sm) and quality merit factor (Q value), for characterizing the AW devices. The Sm expresses the shift in resonance frequency of AW device with a unit mass load, while the Q value defines the sharpness of the resonance peak. A higher Sm means a larger shift in the resonance frequency, while a larger Q value means a sharper resonance peak. A sharper resonance peak results in a higher resolution in determining resonance frequency. Therefore, an AW device with a higher Sm and a higher Q value is highly desirable for developing high performance sensors. Currently, most of AW devices are based on silicon and piezoelectric materials. Recently, the magnetostrictive materials have been introduced as an alternate material for developing high performance sensor platform. Magnetostrictive particles (MSPs), such as strips and bars, have been induced as a new type of AW device. For the devices with this geometry, the MSPs exhibit a Sm about two orders higher than the cantilevers. Both theoretical calculation and the experimental results indicate that the smaller the MSP size, the higher the Sm. To develop high performance sensors, the MSPs in size from nanometer to micrometer are required. We have fabricated magnetostrictive nanobars and nanobar arrays by template based electrochemical synthesis. The diameter of the nanobars ranges from 50 to 200 nm with a length of 2~5 um. The magnetostrictive material used in the study is an amorphous Fe-B alloy. The nanobars are fabricated by electrochemical depositing amorphous Fe-B alloy into ion track-etched polymer membranes. With the dimension in nanoscale, the local microstructure and composition are critical to the performance of nano-magnetostrictive sensors. We propose to characterize the microstructure and composition of nanobars using the EMSL facilities. The nanobars with different size under different deposition condition will be prepared at Auburn University. The local microstructure and composition along the long axis of the nanobars will be characterized using EMSL facilities to study the composition gradient and the effect of the deposition condition. Also, based on the hysteresis loop data, it is found that the Fe-B nanobar arrays exhibit smaller coercivity along long axis direction than that perpendicular to the long axis direction, which is different with the results obtained from other ferromagnetic nanobars. Since the microstructure of the Fe-B alloy is amorphous, the surface energy might play an important role in the magnetic domain switch and the interaction between the nanobars. Therefore, we propose to analysis the surface energy of the electrochemical deposited Fe-B alloy and the interaction between nanobars.
Project Details
Project type
Exploratory Research
Start Date
2006-05-15
End Date
2007-03-22
Status
Closed
Released Data Link
Team
Principal Investigator