Single- and Triaxis Piezoelectric-Bimorph Accelerometers

• Published in: Journal of microelectromechanical systems Vol. 17; no. 1; pp. 45 - 57
• Main Authors: Qiang Zou, Wei Tan, Eun Sok Kim, Loeb, G.E.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-02-2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acceleration; Accelerometers; Bandwidth; Charge; Electrodes; Exact sciences and technology; Frequency measurement; Frequency ranges; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Linearity; Mechanical instruments, equipment and techniques; Micromechanical devices and systems; Parylene beam; Physics; piezoelectric accelerometer; piezoelectric bimorph; Piezoelectric films; Residual stress; Resonant frequency; Signal detection; Transducers; triaxis piezoelectric accelerometer; Yttrium; Zinc oxide; piezoelectric accelerometer; Parylene beam; triaxis piezoelectric accelerometer; piezoelectric bimorph; Accelerometers; Acceleration sensor; Bimorph transducer; Xylene polymer; Residual stresses; Frequency effect; High sensitivity; Piezoelectric transducers; Resonance frequency; Linearity; Piezoelectric actuators; Bandwidth; Piezoelectricity; Zinc oxide; Microelectromechanical device
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2007.909100

This paper describes the novel single- and triaxis piezoelectric-bimorph accelerometers that are built on parylene beams with ZnO films. The unamplified sensitivity and the minimum detectable signal of the fabricated single-axis accelerometer are measured to be 7.0 mV/g and 0.01 g, respectively, over a frequency range from 60 Hz to subhertz. The linearity of the sensitivity as a function of acceleration is measured to be 0.9% in the full scale. A highly symmetric quad-beam bimorph structure with a single proof mass is used for triaxis acceleration sensing and is demonstrated to produce high sensitivity, low cross-axial sensitivity, and good linearity, all in a compact size. The unamplified sensitivities of the X-, Y-, and Z-axis electrodes (of the triaxis accelerometer) in response to the accelerations in X-, Y-, and Z-axes are 0.93, 1.13, and 0.88 mV/g, respectively. The worst-case minimum detectable signal of the triaxis accelerometer is measured to be 0.04 g over a bandwidth ranging from subhertz to 100 Hz. The cross-axial sensitivity among the X-, Y-, and Z-axis electrodes is less than 15% in the triaxis accelerometer. The theoretical analyses of the charge sensitivities and resonant frequencies along with the effects of residual stress on the charge sensitivities are presented for both the single- and triaxis accelerometers.