Effect of surface energy on the sensing performance of bridged nanotube-based micro-mass sensors

The governing equation of a nanotube-based mass sensor is derived with consideration of surface energy, transverse shear deformation, and rotary inertia. Dependencies of the frequency shift and the sensitivity of the sensor on the attached mass are obtained in closed form. The results show that the traditional model, which neglects the surface energy, predicts a higher attached mass and lower sensitivity of the sensor. On the other hand, neglecting the transverse shear deformation and rotary inertia of the sensor will result in a lower prediction of attached mass and a higher prediction of sensitivity of the sensor. It is also found that the surface energy has no effect on the mode shape of the sensor. However, the effect of the location of the attached mass on the mode shape is significant. In particular, if the attached mass is close to the midpoint of the sensor, the frequency shift and sensitivity become very significant.