Study On The Quality Factor Control System Of Microcantilever

As the development of Micro Electro Mechanical System, Microcantilevers, as nano-sensing devices with high sensitivity, are widely used in many areas, such as temperature and humidity sensing in physics, molecule identification in chemistry and DNA molecle imaging in biology. Microcantilevers, which have two working modes: static bending mode and dynamic resonant mode, have been used as transducers to convert the micro changes in nanometer scale into measurable electric or mechanical changes.As an important parameters of microcantilevers, Quality Factor is inversely proportional to the subjected damping of the microcantilever. It has direct effect on the imaging quality of AFM under Tapping Mode and the sensitivity of chemical and biological sensors based on microcantilevers.This subject started from the research on the microcantilever oscillating model, analyzed the microcantilever movement under inspiring force in damping condition and deduced the motion equation of microcantilever in damping condition. Based on the analysis of Quality Factor controlling techniques, a novel Quality Factor control system is designed. This system can be used both in AFM to improve imaging quality in Tapping Mode and in chemical and biological sensor to enhance sensitivity.The main content in the dissertation is as follows:1. Based on the resonant theory of mechanic, founding the law of microcantilever oscillation with and without damping. Analyzing the relationship between the Quality Factor and environmental damping.2. Designing the Quality Factor controlling system. Analyzing the current technology of Quality Factor, setting up the hardware of the controlling system and compiling the controlling software.3. Debugging the circuit and conducting frequency sweeping experiment; comparing frequency curves under different Quality Factor, analyzing the effect of Quality factor control.4. Connecting the Quality Factor controlling system to Veeco Mulimode SPM, imaging in Tapping Mode, analyzing the effect of quality factor on imaging properties.