A multiresonance thickness-shear mode (MTSM) sensor for monitoring the formation of biological thin films

In this work, the development and characterization of a Multiresonance Thickness-Shear Mode (MTSM) sensor operating from approximately 10 MHz to 70 MHz is described which measures the changes in the relative resonant frequency and attenuation as signatures of the sensor. The penetration depth of the acoustic shear waves varies from tens to hundreds of nanometers, depending on the harmonic, so the sensor interrogates the surfaces loaded with biological interfaces at the nano-scale level. The theoretical analysis of MTSM has been developed to model and simulate the signature of the sensor responses at harmonics frequencies. The signature of the entire evaporation-induced deposition processes of biological samples, such as collagen and albumin, including the initial liquid like stage up to the final rigid thin film stage were investigated as case studies and the experimental data were compared with the theoretical simulations. Since the response of the MTSM depends on the interfacial processes, such as mass accumulation (density) or changes in mechanical and geometrical properties (elastic stiffness, viscosity, and thickness) the effect of mechanical and geometrical properties are studied and analyzed using theoretical and experimental data. The MTSM responses showed qualitatively different signatures for collagen and albumin thin films. In conclusion, a MTSM sensor has exhibited many attractive measurement features for studying the kinetics of biological thin film formation processes in real time with high sensitivity and high temporal resolution and a MTSM sensor is capable to provide unique information from different depths in our experimental study.Ph.D., Biomedical Engineering -- Drexel University, 200