Resonance Behavior of Magnetostrictive Sensor in Biological Agent Detection

The growing threat of biowarfare agents and bioterrorism has led to the development of specific field tools that perform rapid analysis and identification of encountered suspect materials. One such technology, recently developed is a microscale acoustic sensor that uses experimental modal analysis. Ferromagnetic materials with the property to change their physical dimensions in response to changing its magnetization can be built into such sensors and actuators. One such sensor is fashioned from Metglas 2826mb, a Magnetostrictive strip actuated in their longitudinal vibration mode when subjected to external magnetic field. Due to mass addition, these magnetostrictive strips are driven to resonance with a modulated magnetic field resulting in frequency shifts. In vibration mechanics the frequency shift for a certain amount of mass will have a tolerance limit based on their distribution and discrete position over the sensor platform. Moreover lateral positioning of same amount of mass does not influence the resonant frequency shift of the sensor. In this regard, this work concentrates on developing a model correlating experimental and numerical simulations to determine the mass of E.coli O157:H7 cells attached to the sensor platform.