Systematic studies on globular proteins using micromachined high frequency bulk acoustic wave resonators

In this paper we use micromachined, high-frequency, quartz bulk acoustic wave resonator arrays to evaluate the physical and viscoelastic properties of adsorbed globular protein films with molecular weights spanning two orders of magnitude. Specifically, changes in the frequency and the Q-factor of the micromachined resonator array were studied as a function of concentration for three proteins, namely Human Serum Albumin (HSA), Immunoglobulin G (IgG) and Human Fibrinogen (Fib) at the fundamental and third resonance modes. The results obtained are interpreted using continuum mechanics approach for multilayer stack on the QCM surface. Discrete changes in the protein adsorption rate constant and the viscoelastic behavior was observed for all the three protein films. The thickness, density, elastic modulus and viscosity of protein layer were successfully obtained through this analysis.