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24 April 2009 Magnetic-field tuning of the frequency and sensitivity response of a magnetoelastic biosensor
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Magnetoelastic sensors exhibit a characteristic resonance frequency upon the application of an alternating magnetic field. In this research, magnetoelastic material was fabricated into micro-sized sensors coated with JRB7 phages to specifically detect Bacillus anthracis spores. Research had shown that the sensor's resonant frequency decreases linearly as its mass increases. As spores are captured, the mass increases. A high mass-sensitivity of up to 7.5 Hz/pg allowed this sensor's use in applications requiring accurate sensing of a very low concentration of B. anthracis spores. A B. anthracis spore weighs about 2 picograms. Two different sizes of sensors, 2000×400 μm and 1000×200 μm, were used in this study. The resonant frequency and the sensitivity of the sensors were found to vary under different magnitudes of DC biasing magnetic field. It was found that both the resonant frequency and the Q-value of the sensed signal increase with an increase of the magnitude of the DC magnetic field until they approach magnetic saturation. As the magnetic field was changed from low to high, it was observed that the signal amplitude increased to a maximum and then decreased to undetectable. Finally, real-time detection of B. anthracis spores is performed under the optimum magnetic field condition.
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Wen Shen, Ramji S. Lakshmanan, Leslie C. Mathison, and Bryan A. Chin "Magnetic-field tuning of the frequency and sensitivity response of a magnetoelastic biosensor", Proc. SPIE 7313, Smart Biomedical and Physiological Sensor Technology VI, 73130L (24 April 2009);

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