Bradley University, Mechanical Engineering, Peoria, IL 61625
DYNAMIC RESONANT BEHAVIOR IN MICROCANTILEVER BEAMS IN FLUIDS OF VARIOUS VISCOSITIES, Stephanie N. Swahlstedt, Shannon J. Timpe*, Bradley University, Department of Mechanical Engineering, Peoria, Il 61625, sjtimpe@bumail.bradley.edu
Microelectromechanical systems (MEMS) resonators, due to their size and sensitivity, can detect small changes in mass, stiffness, and damping through changes in the natural frequency. Resonant peak shifts can be combined with simple dynamic models in order to determine properties such as environmental viscosity or pressure and adsorbed mass in biological sensing applications. The main activity of the current research is to examine the resonant frequency behavior of oscillating MEMS devices under different environmental viscosity levels. The long term goals of this research platform include biosensing for applications in natural product drug discovery. The frequency shifts due to changes in viscosity are phenomenalogically similar to the shifts that are expected to occur when complex botanical extracts are adsorbed onto the surfaces of functionalized microdevices.
Dynamic resonance of micrometer-scale silicon cantilever beams was examined in air and in deionized water. Device oscillation amplitudes were determined when beam-substrate contact resulted in a closed electrical circuit. In air, beams were susceptible to permanent adhesion, detrimentally high temperature increases during current flow, and contact instabilities. In low conductivity deionized water, stable contact is established and easy detection is provided when local heating due to current flow results in liquid vaporization and bubble formation. Ongoing experimentation will examine resonant behavior in additional liquid environments including protein-rich biological solutions. Results are interpreted in light of the principle resonant modes and the suitability for viscometeric measurements and biosensing.
This research was supported by the Heuser Research Award.
[Abstract (DOCX)]