| As a sampling equipment,the pipette is widely used in medical,petroleum,chemical and other fields,which has the characteristics of small volume,high precision and convenient operation.The pipette is designed according to the Hooke principle,and the performance of the spring which is one of the core components relates to the effect of the pipette.In the process of long-term use,due to environmental factors such as temperature,humidity and human factors such as the operation with high frequency,excessive pressure,the elastic curve of spring changes,which affects the precision of pipette.Using substandard pipettes can lead to insufficient or excessive of fluid movement and poor reproducibility,which can lead to deviations in experimental results,lower production efficiency,production accidents.Therefore,in order to guarantee the performance of the pipette,the capacity value should be calibrated periodically.In view of the repetitive workload,low press accuracy,deviation of temperature and batch processing of data during manual calibration of pipettes,an automatic calibration scheme of pipettes based on simulated manual operation is proposed.By measuring the pressure at the two stop points of the pipette button,approximate compression distance is obtained.By comparing data analysis with manual operation,the optimum press distance of simulated manual press is obtained.According to the proposed method,an automatic device for calibrating 4 pipettes simultaneously was developed.The automatic calibration of the pipette is realized by the automatic control of the mechanical module and the intelligent operation of the LabVIEW program in upper monitor.The experimental results show that the repetition decreases 0.0%-0.9% and the relative error decreases 0.1%-0.7% compared with manual operation.And the uncertainty of the volumetric measurement of pipettes is analyzed,which provides effective technical support for the popularization of automatic calibration of pipettes. |
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