Study On Piezoelectric Microcantilever Resonance Frequency Sensing System

As a high sensitive sensor, micro-cantilever has a large scope of application. The first use of it in atom force microscope (AFM) not only provides AFM with atomic resolution but also makes the atomic interaction force between probe and sample detectable. The micro-cantilever has two kinds of working mode, namely deflection mode and resonance frequency mode. The resonance frequency mode has very wide dynamic range and quite high resolution. According to theoretic analysis, the resonance frequency of micro-cantilever is the reciprocal of its effective mass's extracting roots. When the analyte is adsorbed onto the micro-cantilever, the resonance frequency of the micro-cantilever decreases, then the quantitative analysis of the analyte can be done by the detection of the resonance frequency change of the micro-cantilever. The system which uses micro-cantilever as its sensitive component can be set up according to the theory mentioned above.The piezoelectric layer on the piezoelectric micro-cantilever will produce piezoelectric current during vibration and the value of piezoelectric current characterizes the vibration amplitude of the micro-cantilever. This provides an electrical measuring method for the detection of the resonance frequency of micro-cantilever.The main content of the thesis is as follows:1.The vibration theoretical model of micro-cantilever, the relation between the resonance frequency and the mass of micro-cantilever in air and in liquid, the relation between the change of resonance frequency and the mass of detected matter, and the relation between the piezoelectric current which produces during the piezoelectric film's vibrating and the vibration of micro-cantilever;2. The electrical measuring scheme of the resonance frequency of micro-cantilever;3. The design of micro-cantilever biosensor probe, include mechanical structure and pre-amplifying circuitry;4. The design of micro-cantilever biosensor's hardware circuit, include excitation circuit and signal collection circuit;5. The software design of excitation system, signal collection and process system and the software on PC terminal;...