Since the first introduction of the frequency modulation (FM) atomic force microscopy (AFM) by in 1991[1], tremendous progress has been made and it has now been widely used in the field of nanotechnology and nanoscience. At first, it was developed as a method to operate dynamic-mode AFM in a vacuum environment, where the amplitude response of the cantilever (force sensor) to the interaction force becomes extremely slow due to the high Q-factor of the cantilever. Compared to the amplitude modulation (AM) AFM, the FM-AFM has several advantages. The conservative and the dissipative interaction forces are independently detected as the frequency shift and the amplitude change, respectively, in the FM-AFM. Since the self-oscillation loop in the FM-AFM tracks the resonance frequency of the cantilever, the cantilever is always excited at the resonance in the FM-AFM. Therefore, the maximum force sensitivity is always retained in the FM-AFM, while in the AM-AFM the cantilever is excited at the constant excitation frequency, which is close to the resonance frequency at first but deviated by the large interaction force.
We are designing stiff silicon microcantilevers equipped with on-chip piezoelectric actuation and sensing. Unlike the qPlus sensor, silicon based non-contact AFM benefits from batch process. This project is still in the microfabrication process.
[1] Albrecht, T. R., Grütter, P., Horne, D., & Rugar, D. (1991). Frequency modulation detection using high‐Q cantilevers for enhanced force microscope sensitivity. Journal of applied physics, 69(2), 668-673.
Current Researchers
Hazhir Mahmoodi Nasrabadi
Hazhir Mahmoodi Nasrabadi received his B.Sc. in Electrical Engineering from the University of Tehran, Tehran, Iran in 2018 and honored to be among top 10% students. He is currently…