Study On Piezoelectric Microcantilever Sensing Technology

The invention and development of AFM(Atomic Force Microscope) provided anovel sensing device with high sensitivity-microcantilever. Microcantilever has twoworking modes: bending mode and resonant mode. The bending mode measures thestatic strain under an outside force. The resonant mode measures the change of theresonant frequency of the microcantilever. Theoretically, the resonant frequency of themicrocantilever is reverse to the square root of its mass. The increase in mass shifts itsresonant frequency to a lower value. Microcantilever-based sensors, such asbiosensors and chemical sensors have extensive application in field of automobile,aviation, biology, chemistry, and environmental protection, military etc.Starting from the sensing theory of microcantilever, the dissertation provided anovel sensing technology based on piezoelectric microcantilever. The microcantileverpartially covered with a layer of piezoelectric film is used as both an actuator and asensor. Experiments with the designed detecting circuits showed that the differentialamplifying circuit can detect the resonant frequency accurately.The main contents in the dissertation are as follows:1. Analyzing the relation between the resonant frequency and its massthrough theoretic calculation of the microcantilever, putting forward thesensing technology based on piezoelectric microcantilever.2. Analyzing the current induced by the piezoelectric film when themicrocantilever oscillates, designing and debugging the detecting circuit.3. Designing and debugging the actuating circuit for the microcantileverwith frequency spanning from 0 kHz to 80 kHz.4. Designing the piezoelectric microcantilever holder which provided thebasic model for microcantilever biosensor. Besides, the holder can beused in DI-SPM, as well as MEMS dynamic detecting system.5. Building up the resonant frequency measuring system for thepiezoelectric microcantilever. Designing the system software withLabVIEW and carrying out the experiments using the designed circuitand software.