| Accurate pipetting of micro-liquids is the basis for accurate analysis in biochemical analysis,immunoassays,drug testing,forensic science,and other areas.In recent years,with the development of analytical instruments in the direction of high sensitivity,miniaturization,and intelligence,the micro-liquid pipetting unit is moving from the traditional multi-component liquid flow circuit system toward integration.In view of the huge market demand for analytical instruments in our country and the development trend of micropipette liquid-handling systems,this paper developed an integrated precision micropipette module on the basis of theoretical analysis and research and capture of key technologies.In this paper,firstly,the main factors affecting the accuracy of pipetting process are deeply analyzed.Based on this,the dynamic equation of the pipetting process is established,Then the influence of each parameter on the precision and speed of the aspiration system is quantified according to the dynamic model.And the Fluent software is used to apply the droplets,the numerical simulation was performed from the process of detaching the pipette tip to obtain t he effect of different liquid characteristics and flow rate on the drop off.Based on the analysis of the aspiration process and the liquid distribution process,the influence of various factors on the accuracy of the sample addition and the overall execut ion time was obtained to improve the accuracy and efficiency of the sample addition process,and the compensation strategy was determined based on the aspiration error caused by the difference in the liquid level.Secondly,the liquid level detection technology in the pipetting process is studied,and a capacitive liquid level sensor and a pressure level measurement system were constructed based on the principle of pressure and capacitive liquid level detection.The liquid level detection process is explored and implemented.Experimental studies have verified the feasibility of the two liquid level detection technologies and the sensitivity of the sensors,enabling real-time detection of liquid levels with different conductivity levels.Based on the pressure-type liquid level detection technology,a real-time monitoring program for the pipetting process is proposed.By setting up a standard pressure curve model for the pipetting process,abnormal characteristics of the key indicators in the pipetting process were captured and the volatile liquid(ethanol)was the target.A full-time real-time monitoring program for the pipetting process was developed to achieve a drip-free process.On this basis,the development of an integrated precision micropipette module is developed.Based on the analysis results of the aspiration process and the droplet dripping process,the overall design of the micropipette module is proposed.And the development of the drive structure,the sealing structure,the two liquid lev el detection sensors,and the control system are completed.According to the proposed control plan and the interface requirements for subsequent use,the software system is designed and the system integration is completed.Finally,a flexible sample pretreatment platform is used as the object of the pilot study.The experimental results show that the integrated micro-liquid precise pipetting module can be used to add liquids in the volume range of 10?L to 1000?L.The mean values of 10?L,100?L,and 1000?L are 9.90?L,100.05?L,and 1000.88?L,respectively.The reproducibility of samples was 0.1%,0.29%,and 1.8%,respectively.And which enabled the capture of abnormal conditions during sample addition and the anti-drip of the sample adding process. |
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