| The design studies the droplet parameters such as the stability and biological activity,cultures and tests microdroplet(microorganisms,bacteria,etc.)in microfluidic chip microdroplet based on the droplet microfluidic technology.The parameters of different droplets are detected through absorbance detection and fluorescence detection.Microfluidic control is widely used in the fields of biochemistry,medicine and food and has the characteristics of high accuracy,high efficiency and less reagent consumption.The project has the practical application values since it conducts the real-time detection and control system of micro-droplet in the background of the application of microfluidic constantinometer.The paper first outlines the research status and development of microfluidic technology and high-throughput microorganism culture,then,the author explaines the operating principle of micro-droplet detection and provides an overall solution.Two optical detection methods based on photocell and photomultiplier tube are used and the generation of microdroplet is divided before the corresponding hardware and software are designed.Finally,the feasibility of the system is proved by the experimental data after performing the whole machine commissioning,performance test and the application experiment about detection of malachite green solutiont and Cy3 fluorescence detection.Overall system design includes: detector design based on the absorbance of photovoltaic,laser induced fluorescence detector based on photomultiplier tube design,microdroplet counter design based on photoelectric diode,droplet sample design,constant temperature operation module,PC application software design and the upper machine and lower machine communication between Modbus RTU communication protocol design.The paper presents the Absorbance detection system and the principle of laser induced fluorescence detection system,analyzes the requirements of system design,determines the absorbance detector and laser induced fluorescence detector light path design,points out the system functional requirements and determines the technical route of the system technology.The system hardware circuit design includes: 1.The design of the drive circuit of the laser constant optical power output;2.Design of the absorbency detector based on the photocell,including the signal conditioning circuit,the AD signal sampling circuit and the MCU circuit and the design of the peripheral drive circuit;3.Design of laser-induced fluorescence detector based on photomultiplier tube,mainly including signal conditioning circuit and FPGA pulse counting circuit design.System software design includes: 1.Design based on modbus-rtu communication protocol;2.Drive software design based on photocell absorbance detector;3.The driver software design and the photon pulse counting software design of the laser induced fluorescence detector based on the photomultiplier tube;4.Application software design based on Windows system.After the software and hardware,the machine debugging and the performance test,the laser light source output power is stable,the detector performance is up to standard,the PC application software and the next computer communication is accurate,human-machine interface is friendly.Performance testing and application experiments results show that: in the malachite green solution testing experiments,the microdroplet optical detection of absorbance(OD)value measurement range is 0 ~ 4.0 OD,the accuracy is 0.01 OD,linearity > 99.7%,RSD < 0.69%.The maximum number of photons in the Cy3 fluorescence excitation test is greater than 107,and the counting error is less than 0.2 ‰.The generation and segmentation of droplet can both be achieved,the single droplet generation number is 1~ 200,and the accuracy rate is 100 %.The micro-droplet counting and the detection both meet the practical requireme. |
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