摘要
开发了一种在空气中具有几十飞克质量分辨率的谐振式微机械悬臂梁生化质量检测传感器.在悬臂梁上面实现了使用惠斯通压阻电桥检测和洛伦兹力线圈驱动集成结构.与通常的一阶模态谐振传感器不同,为了显著提高传感器特异性反应吸附质量以实现分子水平的检测分辨率,提出了一种二阶弯曲谐振模态优化驱动的方法.在悬臂梁上集成了一种回形针状的驱动电流回路,实现了与第二模态悬臂梁运动两个相反运动峰值相吻合的两处同时反方向驱动.研究中采用硅微机械技术实现了集成谐振悬臂梁的制作,并研制出了高性能的谐振传感器闭环接口电路.在空气中进行谐振实验,与传统一阶模态传感器相比,采用该优化驱动的二阶模态,谐振品质因数从195提高到857,谐振频率从49·156提高到298·132kHz,采用Allen方差的方法对谐振频率噪声进行分析,表明该优化驱动的二阶模态传感器将传统的一阶模态传感器质量分辨率从0·17改善到0·029pg,达到了4个痘病毒的质量分辨水平.
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 massresolution,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.
基金
国家重点基础研究发展规划(批准号:2006CB300405)
国家自然科学基金(批准号:60376038)资助项目~~
关键词
悬臂梁
压阻敏感
电磁激励
AGC式闭环电路
谐振模态
质量检测分辨率
cantilever
piezoresistor
electromagnetic excitation
AGC type closed-loop circuit
resonance mode
massdetection resolution
