Applications of Surface Acoustic Waves (SAW) for Chemical and Biological Analysis

The objective of the proposed thesis is to demonstrate the use of surface acoustic wave (SAW) for a chip based microfluidic system. We utilize this unique SAW chip as a nano-pump to move and mix small volumes of liquids in two dimensional and three dimensional channel geometries for both biological and chemical applications. For instance this technique enables us to analyze the complex interplay of the biochemical and physical properties of cells, proteins and chemicals in blood flow conditions. First of all the surface acoustic waves (SAW) are generated using a piezoelectric substrate where metal transducers are deposited to induce an oscillatory deformation on the chip surface. The SAW which is generated hits the solid liquid interface resulting in an acoustic streaming of the liquid. The result is the observation that the SAW can be used to enhance the mixing of parallel fluid streams on a 3-dimensional microchannel which help alleviate the mixing constraints in microfluidic channels, thereby making it a faster process. In a similar study, a thermoresponsive polymer called pluronics was utilized as an electrically switchable valve for SAW driven microfluidic systems to create obstacles in channels to distort fluid flows and to indirectly induce mixing. Next we utilize a novel SAW driven microfluidic flow chamber to study the physiological conditions of tumor cell adhesion within our blood vessel. Initially, the SAW driven microfluidic flow chamber was successfully utilized to study the mechanical properties of protein stretching in our blood stream. A large glycoprotein complex known as von-Willebrand Factor (VWF) which is involved in triggering the blood clotting cascade was used to demonstrate that upon a critical shear rate (>=1000 s-1) results in conformational changes to VWF increasing its function as an adhesive protein. Although this mechanism is well known to bind platelets, the shear dependent conformational changes to VWF can also promote melanoma cell adhesion is studied using the SAW driven ...