Electrostatic charge and field sensors based on micromechanical resonators

被引:129
作者
Riehl, PS [1 ]
Scott, KL
Muller, RS
Howe, RT
Yasaitis, JA
机构
[1] Analog Devices Inc, Cambridge, MA 02139 USA
[2] Univ Calif Berkeley, Berkeley Sensor & Actuator Ctr, Dept Elect Engn & Comp Sci, Berkeley, CA 94720 USA
[3] Univ Calif Berkeley, Dept Mech Engn, Berkeley, CA 94720 USA
关键词
electrometer; electrostatic fieldmeter (EFM); electrostatic voltmeter; variable capacitor;
D O I
10.1109/JMEMS.2003.818066
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
We have developed highly sensitive electrometers and electrostatic fieldmeters (EFMs) that make use of micromechanical variable capacitors. Modulation of the input capacitance, a technique used in macroscale instruments such as the vibrating-reed electrometer and the field-mill electrostatic voltmeter (ESV), moves the detection bandwidth away from the 1/f-noise-limited regime, thus improving the signal-to-noise ratio (SNR). The variable capacitors are implemented by electrostatically driven resonators with differential actuation and sensing to reduce drive-signal feedthrough. The resonators in the electrometer utilize a balanced comb structure to implement harmonic sensing. Two fabrication methods were employed-a hybrid-technology utilizing fluidically self-assembled JFETs and SOI microstructures, and an integrated process from Analog Devices combining 0.8-mum CMOS and 6-mum-thick polysilicon microstructures. All devices operate in ambient air at room temperature. Measured data from one electrometer with an input capacitance of 0.7 pF indicates a charge resolution of 4.5 aC rms (28 electrons) in a 0.3 Hz bandwidth. The resolution of this electrometer is unequaled by any known ambient-air-operated instrument over a wide range of source capacitances. The EFM has a resolution of 630 V/m, the best reported figure for a MEMS device.
引用
收藏
页码:577 / 589
页数:13
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