| Citation: |
Liu Jian, Li Xinxin, Jin Dazhong, Liu Min, Wang Yuelin, Zuo Guomin, Yu Haitao, Bao Hanhan. Micromachined High Mode Resonant Piezoresistive Cantilever Sensor with Ultrahigh Mass-Sensing Resolution[J]. Journal of Semiconductors, 2006, 27(8): 1496-1502.
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Liu J, Li X X, Jin D Z, Liu M, Wang Y L, Zuo G M, Yu H T, Bao H H. Micromachined High Mode Resonant Piezoresistive Cantilever Sensor with Ultrahigh Mass-Sensing Resolution[J]. Chin. J. Semicond., 2006, 27(8): 1496.
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Micromachined High Mode Resonant Piezoresistive Cantilever Sensor with Ultrahigh Mass-Sensing Resolution
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Abstract
An ultrasensitive resonant cantilever sensor with a mass-resolution of tens of femtograms is developed for application in an air environment with a piezoresistive bridge and a metal coil integrated on the same cantilever.To improve mass-resolution,an optimized clip-style Al loop is fabricated on the cantilever especially for the 2nd flexural resonance mode.Such excitation provides two-point driving forces that match the 2nd mode shape-function of the cantilever deflection.In air,the resonant cantilever in the 2nd mode with the clip-style excitation shows a significantly increased quality factor of 857,while the 1st mode cantilever excited by conventional excitation shows a quality factor of 195.A closed-loop feedback circuit is developed to maintain the cantilever’s resonant in self-oscillation.By using Allen variance analysis,the resolution of the resonant sensor in air is improved from 0.17pg to 0.029pg by optimized excitation for the 2nd mode,and the resolution of 4 vaccinia viruses is achieved. -
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