In this study, we use finite element method (FEM) analysis to show the possibility of a microsystem capable of detecting and analyzing liquid and solid media in minute amounts using surface acoustic wave (SAW) devices with microcavities. The SAW delay lines on ST-cut quartz operating with Rayleigh waves are simulated in a 2-D space in the high frequency range of 200 MHz. Liquid medium is a mixture of glycerin and water, whereas the solid samples carry the elastic properties of polystyrene. The platform works with liquid sample volumes less than 10 pL and with solid microbead samples with a diameter of 10 µm. In mixtures of glycerin and water between 40% and 90% a roughly linear and reasonable relation exists for velocity of sound and density, and at this range, a maximum phase change of -0.77 degrees was obtained per glycerin percent. A non-linear phase response was obtained with respect to microbead stiffness for which a linear fit provides a slope of -69.4 degrees per GPa around 3 GPa elasticity.
Journal: TechConnect Briefs
Volume: 2, Nanotechnology 2014: MEMS, Fluidics, Bio Systems, Medical, Computational & Photonics
Published: June 15, 2014
Pages: 73 - 76
Industry sector: Sensors, MEMS, Electronics
Topics: MEMS & NEMS Devices, Modeling & Applications