Document Type

Conference Proceeding

Language

eng

Format of Original

4 p.

Publication Date

1-29-2012

Publisher

Institute of Electrical and Electronics Engineers

Source Publication

2012 IEEE 25th International Conference on Micro Electro Mechanical Systems (MEMS)

Source ISSN

1084-6999

Original Item ID

doi: 10.1109/MEMSYS.2012.6170261

Abstract

This paper introduces an electrothermally actuated, piezoresistively detected, silicon-based tuning fork geometry as a suitable platform for resonant sensing applications in air. Operated at their fundamental tuning fork mode (fTF ≈ 400 kHz), in which the two tines oscillate with 180° phase shift to each other, the devices exhibit Q-factors of 4000-4200 in air. By properly choosing the locations of the integrated excitation resistors as well as the four piezoresistors forming a Wheatstone bridge, output signals stemming from low-frequency out-of-plane vibration modes of the microstructure are successfully suppressed. As a result, the tuning forks can be easily embedded into an amplifying feedback loop, achieving short-term frequency stabilities in air as low as 0.02 ppm (0.008 Hz) for gate times of 1 sec. Coated with a chemically sensitive polymer film, the tuning forks were used as mass-sensitive sensors with detection limits in the low-ppm range for toluene.

Comments

Accepted version. Published as part of the proceedings of the conference, 2012 IEEE 25th International Conference on Micro Electro Mechanical Systems (MEMS), 2012: 607-610. DOI. © 2012 IEEE. Used with permission.

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