Publication Date



Open access

Embargo Period


Degree Type


Degree Name

Doctor of Philosophy (PHD)


Electrical and Computer Engineering (Engineering)

Date of Defense


First Committee Member

Onur Tigli

Second Committee Member

Sung Jin Kim

Third Committee Member

Michael R. Wang

Fourth Committee Member

Mei-Ling Shyu

Fifth Committee Member

Tan A. Ince

Sixth Committee Member

Ram H. Datar


The platform presented in this study exploits high frequency acoustic interaction and uses direct coupling of Rayleigh type SAWs with various samples placed inside microcavities to analyze their structural properties. The proposed microsystem was analyzed using finite element methods. Prototype devices were fabricated on quartz and lithium niobate in a cleanroom environment. Soft microprobes and microchannels were fabricated out of SU-8 and PDMS, respectively. Experimental results are given first for analysis of high glycerin content in deionized water as wells as counting and size differentiation of polystyrene microbeads. Ultimately, biological cells are sensed and characterized. After tumor cells in media are transported to and trapped in microcavities using soft microprobes, the proposed platform uses SAW interaction between the substrate and the cells to extract their mechanical stiffness based on the ultrasound velocity differentials. Small populations of various types of cells such as MCF7, MDA-MB-231, SKBR3, and JJ012 were characterized and characteristic moduli are estimated for each cell population. In conclusion, the results indicate that high frequency stiffness modulus is a possible biomarker for aggressiveness of the tumor and that microcavity coupled SAW devices are a good candidate for non-invasive interrogation and high frequency biophysical studies of single cells. The proposed system is a successfully miniaturized ultrasonic biosensor and can be integrated with microchannels to obtain higher throughput upon refinement of the design as evidenced by the initial results with microfluidics. Improvement in performance and signal strength is also shown to be possible through matching circuits as demonstrated.


surface acoustic wave biosensors; rayleigh waves; microcavities; cancer research; single cell analysis