Vibrational characteristics of defective single walled BN nanotube based nanomechanical mass sensors: Extended defect or dislocation line

• We performed vibrational characterization of the defective single walled boron nitride nanotube considering dislocation line.
• The dislocation line as a defect is simulated using molecular structural mechanics based finite element modeling approach.
• The mass sensitivity limit of variation, 10−25 kg to 10−23 kg can be obtained using defective SWBNNT based sensor system.
• The presence of dislocation line alters the vibrational characteristics of SWBNNT.

In this paper, vibrational characteristics of a single walled boron nitride nanotube (SWBNNT) has been explored considering presence of extended defect/dislocation line to use SWBNNTs as mass sensors. Resonant frequency based analysis of SWBNNT with presence of extended defect at different locations and of different lengths in percentage of total length of nanotube has been performed using molecular structural mechanics based finite element (FE) model. The cantilevered configuration of zigzag (14,0) form of SWBNNT with presence of extended defect having different lengths (10%, 20% and 30%) at different location is modeled considering it as a space frame structure with three dimensional elements and point masses, such that the proximity of the model to the actual atomic structure of nanotube is significantly retained. The finite element simulation approach is used to analyze the effect of presence of extended defect on the resonant frequency based mass sensing. The present molecular structural mechanics based simulation approach has been validated using the continuum mechanics based analytical results for defect-free SWBNNT considering attached mass at the tip of the cantilevered SWBNNT, and obtained simulation results are found in excellent agreement with the analytical exact results. SWBNNTs of two different aspect ratios (length/diameter) 10 and 20, are considered to analyze the effect of size on the resonant behavior and sensor sensitivity. An increase in resonant frequency has been observed when the position of the extended defect moves from the fixed-end to the free-end of the cantilevered configuration of SWBNNTs. Also, resonant frequency shift analysis with respect to defect-free SWBNNT is performed for different magnitude of the nanoscale mass at the free end and obtained results indicate that the mass sensitivity limit of 10−25 kg can be obtained for the presence of extended defect at the free-end as well as at the fixed-end, while for the presence of extended defect at the middle of the length of the nanotube mass sensitivity limit increases to 10−23 kg. Using present molecular structural mechanics based simulation approach, different atomic structures with extended defect as well as boundary conditions can be effectively simulated.