Research On Key Technology Of Miniature Automatic Chemiluminescence Immunoassay Analyzer

More than 80%of the global medical diagnosis is in the field of in vitro diagnosis.The in vitro diagnosis is fast,simple,clean,pollution-free and less harmful to the human body.The fully automatic chemiluminescence immunoassay analyzer is one of the important instruments for clinical in vitro diagnosis.It involves the contents of many disciplines such as motion control technology,mechanical processing technology,micro-pipetting technology,temperature control technology,etc.,and most of these technologies are still monopolized by foreign companies.Related products in domestic R&D has a large gap with foreign products.In order to break this situation,a small in size and cost-effective miniature fully automatic chemiluminescence immunoassay analyzer was designed,and some key technologies were analyzed and studied to complete the corresponding module design.The structure of the three-axis mechanical arm combined with the micropipette replaces the traditional sample needle and reagent needle system,so that the volume of the whole instrument is greatly reduced.This paper describes in detail the design ideas and methods of the mechanical arm sample motion control system,micro pipette and temperature control system:The mechanical arm sampling system is a multi-axis linkage motion control system.In this paper,the design scheme of the mechanical structure,the drive circuit,the single-axis control algorithm and the multi-axis linkage control scheme are studied.The three-axis drive circuit based on ARM microcontroller is designed according to the requirements.The improved S-type acceleration and deceleration algorithm is used to improve the smoothness of the stepper motor and increase its applicable range range.In multi-axis control,the motion error of the manipulator in the xOy plane is corrected by the cross-coupling control algorithm.In the positioning accuracy experiment,the oscillation and noise during the operation of the manipulator are significantly reduced,and the positioning accuracy of the manipulator in the xOy plane was obtained as 0.114 mm,the repeat positioning accuracy is 0.097 mm;the z-axis positioning accuracy was 0.060 mm,and the repeat positioning accuracy was 0.046 mm,which meets the instrument design requirements.The performance of a micropipette is the key to the accuracy of the analyzer.The overall design of the micropipette mechanical structure,circuit,workflow program.The Kalman filter is used to filter out the noise in the pressure signal,and the internal pressure change of the pipette is detected in real time to realize the liquid level detection,TIP head blockage and sample bubble monitoring function,and a bubble recognition algorithm based on peak-to-valley time is proposed to take place of the wavelet transform recognition method,so that the computing and storage load of the microprocessor is reduced.The position-speed double closed loop PID algorithm is used to improve the stability and positioning accuracy of the piston motion.In the experiment,the correct rate of pipette identification for bubbles containing and non-bubble samples were 99%and 93%,respectively,the recognition rate was high,but there was still some misidentification.In the test point test of 10?L,50?L and 100?L,the repeatability errors were 0.61%,0.40%,and 0.33%,respectively,and the accuracy errors were 1.65%,1.10%,and 0.85%,respectively.The repeatability accuracy approached the Tecan air dispalcement pipptt,but further explore still needs to be conducted in terms of accuracy.The reaction disk is the place where the immune reaction occurs,and its temperature stability and repeatability are essential.The H-bridge drive circuit is designed and its bootstrap circuit parameters are determined.The CLC filter is used to determine its component parameters through circuit simulation,so that the output voltage ripple of the drive circuit is reduced from 75 mV to less than 30 mV.The Smith predictor combines with the fuzzy PID algorithm to compensate the pure hysteresis in the reaction temperature control system and improve the anti-interference ability in the temperature control process.Finally,the reaction tray temperature was increased from 20 ? to 37 ? in 25 minutes,and the reaction tray temperature was always stable at(37 ± 0.1)0C during long-term stability experiments.In the cuvette incubation experiment,the traditional PID algorithm was compared with the fuzzy PID control.The reaction plate temperature was reduced to 35.5 ? in traditional PID control,but was reduced to 36.5 ? in fuzzy PID control,and the reaction cup incubation time was reduced from 8.3 minutes to 6.6 minutes.The disk temperature recovery time was reduced from 8.6 minutes to 6.6 minutes,and the dynamic performance and anti-interference ability of the system with fuzzy PID control was significantly improved.