Effective Surface Enhancement of Nanomechanical Disk Resonators Using CNT for Mass Sensing Applications

This work presents fabrication of thermal-piezoresistive nanoelectromechanical (NEM) silicon disk resonators and their characterization as highly sensitive mass sensors. Forests of carbon nanotubes (CNT) have been grown on top surface of the resonators increasing the effective surface area of the resonator which in turn increases adsorption capacity of the sensor in molecular or particulate detection applications. To characterize the mass sensitivity, devices were exposed to a solution of manganese sulfate (0.02M) for different deposition times. MnO
₂
nanoparticles were gradually deposited on CNTs adding to the resonator mass. The resonance frequency shift due to added MnO
₂
mass was recorded accordingly. The calculated mass sensitivity from experimental results shows mass sensitivity as high as 5 Hz/femtogram for a 20μm diameter disk resonator.