PVDF Properties Research And Micro Force Sensor Design

The piezoelectric micro-force sensors offer a lot of advantages for MEMS applications such as low power dissipation, high sensitivity, and easily integrated with piezoelectric micro-actuators. In spite of many advantages above, the research efforts are relatively limited compared to piezoresistive micro-force sensors. In this thesis, in order to increase the sensitivity of the piezoelectric micro-force sensors, and integrate with the piezoelectric micro-actuators, a PVDF (polyvinylidene fluoride) thin-film micro-force sensor is systematically studied in terms of the deposition and characterization of the PVDF thin-film, design, fabrication and test of the micro-force sensors based on micro-cantilever structures. In this paper, a novel sensing scheme for IPMC actuators is proposed by integrating an IPMC with a PVDF thin film. The problem of feed-through coupling from the actuation signal to the sensing signal, arising from the proximity of IPMC and PVDF, which presents a significant challenge in real-time implementation, to reduce the coupling while minimizing the stiffening effect, the thickness of the insulating layer is properly chosen; and also we introduce the PVDF film with probe together, constituting the micro force sensor biological operating system,through the film for calibration, to realize the power of detection.In this paper, the sensing theory of micro-cantilever is systematically analyzed, we analyze the force and displacement of PVDF with ANSYS, a design for PVDF micro-cantilever between force, deformation and sensing voltage is also provided by modal analysis based on piezoelectric effect, deformation and sensing voltage is also provided by modal analysis based on piezoelectric effect. This lays a foundation for future development.Sensing and frequency characteristics of piezoelectric-film have been analyzed using the NI-DAQ PCI6221by Lab VIEW virtual instrument. Based on the analysis above, sensing circuits (differential charge amplifier and micro-current amplifier) have been designed and debugged. And then, a complete testing platform for PVDF/IPMC is developed. Since the sensing signal is very weak, this paper designes a high-sensitivity sensor probe, including preamplifier, differential circuit, voltage upgrading circuit design. At last, a developed IPMC/PVDF structure with compensation algorithm is presented.In order for miniaturization, we discuss the principle and implementation of real-time signal acquisition and processing with DSP. This paper builts up the micro-force signal detecting system software for the piezoelectric micro-cantilever,carrying out the experiments using the designed circuit and software.