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Abstract:
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We report the design and fabrication of a micro -mechanical oscillator for use in extremely small force detection experiments such as transverse force measurements of a moving vortex and Nuclear Magnetic Resonance Force Microscopy (NMRFM ) . We study the basic physics of the double torsional mechanical oscillator , and pursue double torsional oscillators with small spring constants , high resonance frequencies , and high quality factors . Using a series of semiconductor manufacturing techniques , especially using the electron -beam lithography technique , we successfully micro -fabricate double torsional mechanical oscillators from silicon -on -insulator wafers . We conduct characterization experiments to extract important parameters of a mechanical oscillator , including the resonance frequencies , spring constants , and quality factors . We focus on the four typical resonance modes of these oscillators , and then compare the force detection sensitivity of each mode . Eventually we apply these force sensitive oscillators to gold micro -mass measurements , and achieve very small mass detection . In the future we are going to continue to micro -fabricate thinner oscillators to reduce the spring constants , and improve the quality factors by designing more suitable geometric shapes and by pursuing annealing studies . Thus , we might be able to achieve single nuclear spin measurements using NMRFM . |