Study On The System For Testing And Calibrating MEMS Piezoresistive Micro Contact Probe

In recent years, as the rapid development of micro/ nano machining technology, it comes higher requirements to measuring instruments in machining process. The old coordinate measuring machines(CMM) only have uncertainties around micrometers, which cannot fit the requirements mentioned above. Therefore, new Nano-CMM that has nanometer resolution and is able to use for measuring tiny dimensions, positions and other characteristics of surface appearance, is a necessary tool in micro/ nano measuring field in the future. A Nano-CMM is mainly composed of platform and probe. The platform realizes displacement and positioning with wide range and high precision. The probe receives tested signals and then transforms them.To a MEMS piezoresistive probe which designed by this project group, a new Nano Positioning and Nano Measuring Machine(NMM) system was used to test and calibrate the practical performance of it in this paper. Based on the requirements of signal testing, a data collection circuit and software of testing&calibration were designed, which improved in performance and efficiency of the system. Put the finished system in testing&calibrating experiments, software and hardware parts of the system all run smoothly and satisfied testing results were achieved.The main achievements of this paper include:(1) With the method of emulation and comparison, established the structural features of MEMS sensor used on probe. According to the principle of piezoresistive effect, designed the lay-out and connection of piezoresistances. To the sensor which had been manufactured, did packaging, center positioning and the paste of probe stick. Assembled the piezoresistive probe.(2) Suggested the system plan for calibrating probe. Using the NMM with high resolution as positioning platform, the system still included probe module, data collection circuit, CCD monitor and testing&calibration software, etc.(3) Designed and debugged the automatic data collection circuit to probe signals, which core was single-chip computer. It mainly included data adjusting, A/D transforming, data saving, LCD displaying and block of data transferring.(4) For the requirements of calibration softwares, designed NMM operating and LabWindows high-position computer programs. Programed on single-chip computer. (5) Put the finished system in testing&calibrating experiments. Calibrated the sensitivity, operating range and non-linear error of the probe. Tested the 3-direction output coupling, noticed some problems of probe design and suggested specific improvement measures for the system.