The resonant behavior of silicon tubes under two-phase microfluidic conditions with both microbeads and gas bubbles

This paper examines the behavior of the gain, Q and frequency of resonating microtubes during two-phase, both liquid-gas and liquid-solid, fluidic conditions. The presence of both gas bubbles and solid particles are found to shift the resonant frequency and dampen the resonator signal under static conditions. Going from air to a pure liquid depressed the resonator Q-value by 7-50%. The addition of a significant amount of a second phase, either gas or solid could depress the Q-value by 96% from that of the pure liquid filled resonator. New Q loss mechanisms for microresonators were uncovered, via either internal liquid damping or two-phase damping. Ferromagnetic beads in an external magnetic field are observed to have a significant, variable affect on the gain and Q of the resonator and bead motion of the vibrating microtube. A variety of sensor and transducer applications for the results will be discussed and include Coriolis mass flow, density, chemical concentration, lubricity and viscosity measurements, testing of slurries and carbonated or aerated liquids, mixing, and cell lysing. (c) 2006 Elsevier B.V. All rights reserved.