Document Type
Article
Publication Date
4-20-2015
Keywords
resonator, Q factor, motional resistance, piezoelectric transducer, mass loading, sensitivity, limit of detection
Digital Object Identifier (DOI)
https://doi.org/10.3390/act4020060
Abstract
In this work, we have investigated the design, fabrication and testing of ZnO-on-SOI fourth-order contour mode disk resonators for mass sensing applications. This study aims to unveil the possibility for real-time practical mass sensing applications by using high-Q ZnO-on-SOI contour-mode resonators while taking into account their unique modal characteristics. Through focused ion beam (FIB) direct-write metal deposition techniques, the effects of localized mass loading on the surface of three extensional mode devices have been investigated. Ten microfabricated 40 mm-radius disk resonators, which all have a 20 mm-thick silicon device layer and 1 mm-thick ZnO transducer layer but varied anchor widths and numbers, have exhibited resonant frequencies ranging from 84.9 MHz to 86.7 MHz with Q factors exceeding 6000 (in air) and 10,000 (in vacuum), respectively. It has been found that the added mass at the nodal locations leads to noticeable Q-factor degradation along with lower induced frequency drift, thereby resulting in reduced mass sensitivity. All three measured devices have shown a mass sensitivity of ~1.17 Hz·fg−1 at the maximum displacement points with less than 33.3 ppm of deviation in term of fractional frequency change. This mass sensitivity is significantly higher than 0.334 Hz·fg−1 at the nodal points. Moreover, the limit of detection (LOD) for this resonant mass sensor was determined to be 367 ag and 1290 ag (1 ag = 10−18 g) for loaded mass at the maximum and minimum displacement points, accordingly.
Rights Information
This work is licensed under a Creative Commons Attribution 4.0 License.
Was this content written or created while at USF?
Yes
Citation / Publisher Attribution
Actuators, v 4, issue 2, p. 60-76
Scholar Commons Citation
Rivera, Ivan; Avila, Adrian; and Wang, Jing, "Fourth-Order Contour Mode ZnO-on-SOI Disk Resonators for Mass Sensing Applications" (2015). Electrical Engineering Faculty Publications. 2.
https://digitalcommons.usf.edu/ege_facpub/2
Comments
The authors published an addendum to this article in 2016. It is located at https://doi.org/10.3390/act5040024.