A Study On Measuring Technology Of AFM Microcantilever With Quality Factor Controlled In Tapping Mode In Liquid

Since it was invented, the measuring technology of Atomic Force Microscope(AFM) has been rapidly developed, and its applications are gradual abroad. Today, AFM has applications in physics, chemistry, metal, semiconductor, microelectronic, nanomaterial, biology, life science, and so on. At the same time, someone has made the microcantilever of AFM as sensor to detect biological and chemical reaction, and therefore AFM has become a main instrument in microscopic kingdom.There are 3 work modes in AFM, Contact Mode, Non-Contact Mode, Tapping Mode. Because it has less damage to sample, Tapping Mode has especial advantage in detecting biological and chemical reaction. However, when Tapping Mode is applied in liquid, the quality factor of microcantilever will be greatly reduced, which will reduce measuring precision of microcantilever and even make microcantilever not work. Hence increasing quality factor become the key of increasing detecting effect of Tapping Mode in liquid.In this text we have analyzed the theory of quality factor controlled, designed the circuit and linked the circuit to MultiMode SPM of DI company. We have experimented and proved our theory.Main studying content:Analyzing the reason why the quality factor of AFM microcantilever will be reduced in Tapping Mode in liquid and searching the method of increasing quality factor.Designing the circuit of quality factor controlled and linking the circuit to AFM.Proving this system's performance in experiment.Analyzing the effect and making a conclusion.