Simultaneous determination of the mass and position of attached particles using a micro-beam resonant mass sensor with axial pre-tension

In this work, we present a method to simultaneously detect the mass and the position of an attached microparticle using a bridge-type micro-beam resonant mass sensor under axial pre-tension. Simultaneous detection of the mass and the position is innovatively enabled by deliberately varying the axial pre-tension, utilizing only the fundamental frequency. As an important dissipation mechanism, thermoelastic damping (TED) in micro-/nano-resonators imposes an upper limit on the quality factor and the minimum detectable mass of resonant mass sensors. Accordingly, TED of micro-/nano-beam resonant mass sensors with axial pre-tension is analyzed by the thermal energy method, and heat conduction along both the thickness direction and axial direction is considered. The effects exerted by the pre-tension on the sensitivity and TED of resonant mass sensors are systematically investigated. Numerical results reveal that axial pre-tension not only enhances the mass sensitivity but also reduces the TED of the resonant mass sensor. Furthermore, effects of other factors, such as aspect ratio, vibration mode, mass and position of the attached particle, on TED are examined as well. This work provides a theoretical guidance to the extraction of mass of microparticles, cells and molecules by experiment.