Design And Research Of Automatic Sampling System For Liquid Processing Workstation

Automatic liquid handling platform is one of the necessary tools to help complete the high-throughput experimental process,which can help the laboratory to build a standardized experimental process and ensure the accuracy and repeatability of the results.The automatic sampling system is the most basic core function module with the highest degree of participation.It is mainly responsible for the automatic sample addition and accurate distribution of samples,which determines the working efficiency,degree of automation and the platform's reliability of results.Aiming at the domestic demand,an automatic sampling system for high efficiency and compactness is designed and developed on the basis of theoretical research.In this paper,the working principle of platform and air displacement suction technology was explored,and it was concluded that reducing or eliminating the influence of specific factors on liquid operation is the key to break through the performance bottleneck of the existing technology.At the same time,two sensorassisted technologies were deeply studied,including the principle and application of liquid level detection based on pressure sensor and capacitance sensor,and the formulation of liquid level detection process.The feasibility of real-time monitoring of various abnormal conditions(such as air suction,bubble and blockage,etc.)based on pressure sensor was verified by experiments.This provides a theoretical basis for fully understanding the working mechanism of the system,reasonably determining the control flow and guiding the design of the system.Then,through a lot of investigation and analysis,the overall mechanical design scheme of the automatic sampling system was gradually established.According to the domestic demand for workstations with automatic sampling system,the target system was divided into three independent devices according to functions.The typical mechanical transmission structures were compared and analyzed,and the mechanical structure suitable for this subject was determined,and the specific structural parameters were determined to meet the requirements of positioning control and precision.The assembly drawing of the sampling system was established by using UG software,which provided a theoretical basic model for the subsequent structural improvement and manufacturing.On this basis,the software ADAMS was used to carry out the kinematics simulation analysis of the CAM distance adjusting mechanism.The simulation results which basically consistent with the results of subsequent experimental measurements show that the required functions are realized,and the system has excellent stability and reliability,At the same time,the factors that affect the sampling accuracy were deeply analyzed.Fluent software was used to quantify the influence of each parameter on the sampling system accuracy and speed,so as to improve the processing accuracy and efficiency.Finally,based on the original workstation,a simplified hardware platform of the automatic sampling system was designed and built for experimental research.The results show that the maximum error of channel spacing adjustment is less than0.2mm,and the maximum error of vertical movement positioning is 0.65 mm.The abnormal alarm function has good reliability.The sampling accuracy and repeatability of the system meet the national metrological verification regulations,which can meet the practical requirements.