Numerical analysis for design optimization of microcantilever beams for measuring rheological properties of viscous fluid

Abstract

The precise measurement of rheological properties is a demanding problem in various field of engineering. Occasionally the available sample volume of interest may be sufficiently small where the conventional methods of measuring rheological properties are inappropriate. Consequently, there is a growing interest in the use of MEMS devices to measure the required properties, especially with an aim of encouraging high throughput. During this research, the dynamic response of micro cantilever beams is demonstrated to characterize the rheological properties of viscous materials. First, the dynamic response of a mini cantilever beam partially submerged in air and water is measured experimentally for different configurations using a duel channel PolyTec scanning vibrometer. Next, finite element analysis (FEA) method is implemented to predict the dynamic response of the same cantilever beam in air and water, and then compared with corresponding experiments. Once the model is validated, further numerical analysis is conducted to investigate the variation in modal response with changing beam dimension and fluid properties. Results obtained from this parametric study can be used for sensitivity analysis and to design the optimized MEMS based test set up for measuring the rheological properties of viscous fluid and of any soft viscoelastic materials such as biofilm. Miniaturization of the measuring instrument is necessary so that small sample volume can be used to perform the desired test.