Design and Characterization of a CMOS MEMS Capacitive Oscillator for Resonant Sensing in Liquids

作者：Chiang Che Hao^*; Chou Mu Chi^*; Hsieh Ping Hsuan^*; Lu Michael S C^*

来源：IEEE Sensors Journal, 2016, 16(5): 1136-1142.

DOI：10.1109/JSEN.2015.2499256

• CMOS
• MEMS
• capacitive oscillator
• liquid

Liquid properties can be studied through monitoring the in-liquid resonant behavior of micromechanical oscillators. This paper presents the first attempt to implement capacitively transduced micromechanical oscillators in a complementary metal-oxide-semiconductor (CMOS) process for in-liquid operation. The parallel-plate drive and sense capacitors have a 2-mu m gap and 1-mu m dielectric sidewalls to protect the electrodes. A wide-range CMOS phase-locked-loop circuit is designed to sustain oscillation in face of the large resonance shift while operating in liquids. Measurements show that the capacitive micro-resonator is driven to oscillation at 51.2 kHz in air. The resonant frequency increases to 78.1, 121.9, and 203 kHz in ethanol, isopropyl alcohol, and deionized water, respectively, due to the elastic squeeze-film damping effect and individual liquid properties. The large resonance shift in liquids can be utilized for sensitive bio/chemical detection in the future.

• 出版日期2016-3-1
• 单位清华大学; 中国科学院电工研究所