Characterization of PMMA Polymer using Thickness-Shear Mode Resonator

This thesis investigates the mechanical properties of PMMA polymer using a 9- MHz thickness-shear mode quartz resonator. The PMMA polymer can be used as a chemically sensitive coating material in implementing biochemical sensors and as a waveguiding layer in guided SH-SAW devices. PMMA is suitable as a chemical sensing layer because of its analyte sorption ability and good resistance to acid and environmental deterioration. It is a good waveguiding layer for guide SH-SAW devices because of its low acoustic velocity and ability to trap the acoustic energy near the device surface as well as provide protection for the interdigital transducers of the SH-SAW devices. The electrical response of the PMMA-coated TSM resonator depends on the polymer density, viscoelastic properties and mass loading. The electrical response of the PMMA-coated device was examined at the fundamental frequency of the device. The device was spin-coated with PMMA polymer to a thickness of 18.72 μm. A network analyzer was used to operate the device and measure the admittance responses for both the bare device and PMMA-coated device. The complex shear modulus parameters (storage modulus and loss modulus) were computed from the admittance measurements. Changes in the shear modulus parameters were induced by temperature variation and the behavior of the shear modulus was investigated for the glassy and rubbery states of the PMMA polymer. The temperature behavior of the extracted storage and loss moduli showed good agreement with publications from other extraction methods