Experimental Research On Micro-Force Reproduction Using Electrostatic Field

With the rapid development of the new materials, microelectronics, and biological and other high-tech industries, in which ultra-micro-nano-level measurement of force plays a key role, it is urgent to develop measurement standard of micro-nano force to trace to the SI.An ultra-micro-force tracing program based on electrostatic field is presented in this paper. The feasibility of the measurement program is analyzed theoretically and the experimental platform is built to verify the correctness of the principle. The main research contents and work are as follows:1. Summarized the significance of research about ultra-micro-force and analyzed the development about it at home and abroad in this paper. The project's contents and purpose are then determined.2. The mathematical model of capacitance gradient of cylindrical capacitive sensor is derived based on electromagnetic theory. Electric field distribution and potential between internal and external electrodes are analyzed numerically. It provides theoretical basis for the follow-up work.3. The capacitance gradient are analyzed through the finite element method analysis software, Ansoft Maxwell. And the factors ,which effect on capacitance gradient, such as size of plate,partial axial and plate tilt are analyzed qualitatively.4. Gem blade, balance lever structure and limiting mechanism are designed to sustain the electrodes ,Set up the experimental mechanical device.5. To measure the small capacitance of the cylindrical capacitive sensor, a PCB board is designed with AD7747,which is a high-precision, integrated capacitance measurement chip.CY7C68013 chip .USB2.0 transmission is used to connect the AD7747 and PC to transport measurement data. PC interface is designed based on VC ++, with which PC can display the capacitance value real time and execute the control to AD7747.6. The measurement system platform is built to measure the gradient of the capacitance. Static electricity force test is completed. Experimental results show that the gradient and the electrostatic capacitance measurement results are generally consistent with the theory result. The factors affecting its accuracy are analyzed and summarized, and suggestions for improvement are put forward.