Research On Automatic Micro-nano Sensing System Based On Intelligent Microfluidic Chip

Microfluidics is one of the advanced research fields which is interdisciplinary.By integrating the basic experimental operations of sampling,mixing,reaction,sample separation and detection in the fields of medicine,biology and chemistry into the centimeter scale chip,the technology has replaced the functions of the traditional biochemical detection laboratory to some extent.Therefore,microfluidic sensing system has great application prospects in the fields of biological detection,drug screening,pollutant monitoring and so on.In recent years,with frequent food safety accidents and serious clinical reactions,food safety has become a hot topic in modern society.At present,the conventional food detection instruments are expensive and time-consuming,and also rely on professional technical personnel to operate.Moreover,many food pathogenic factors must be identified,detected and monitored in the early stage by effective and effective methods.Therefore,the conventional instruments can not meet the requirements of fast,sensitive and authentic detection,and can not realize the automatic detection process.And for microfluidic chip,how to realize the function of particle separation,single capture,fluid mixing and detection is the main problem to be solved.In view of the above problems,the thesis designs a micro nano sensor system based on microfluidic chip technology,and studies the biochemical reaction process of automatic mixing,separation and detection in the system,which is of great significance to the rapid detection of food safety.The main work of the thesis is as followsFirstly,aiming at the problems of automatic mixing,transportation and sorting,the dynamic model of magnetic beads in micro flow channel is established,and the closed-loop control method in micro nano sensor system is proposed.Magnetic beads play an important role in the miniaturization of rapid detection system.In the microfluidic channel,magnetic beads are used as the transmission carrier of automatic process,and the basic law of magnetic beads transmission in microfluidic channel is explored.Then an electromagnetic coil with special structure is designed,and the analytical model of magnetic field is solved.The force acting on the magnetic bead in the microfluidic channel is analyzed,and the kinematics model of the magnetic bead in the microfluidic channel is established.An active disturbance rejection controller(ADRC)for bead position control is designed,and the transmission capability of beads in microfluidic channel is studied.Then,aiming at the integration of automatic detection,a detection scheme of micro nano sensor system is proposed.Based on the three electrode system,the telephone micro nano sensor has the advantages of short time,high sensitivity,quantitative accuracy and not easy to be interfered by the external environment,which can realize fast,low cost and on-line detection.In the thesis,microelectrode is integrated into microfluidic chip to construct micro nano impedance sensor,and then the detection module of the sensor system is constructed according to the scheme,and the evaluation index of the designed sensor is established.Then,based on the designed sensing detection scheme,the channel composition and size of the microfluidic chip are determined,and the microelectrode is fabricated on the glass substrate by micro processing technology,and finally the chip is packaged by plasma bonding equipment.Finally,the airtightness of the chip is verified.Finally,an experimental platform is built to explore the experiment.For the micro nano sensor system proposed in the thesis,several experiments are carried out: 1)control the magnetic beads in the mixing area of the microfluidic chip to verify the mixing ability of the microfluidic system;2)The magnetic bead is used as the controlled object to verify the transport capacity of the microfluidic system;3)The flow direction of the magnetic beads is controlled at the multi bifurcation channel,and the separation ability of the magnetic beads in the microfluidic system is verified;4)The detection performance of the integrated sensor is verified by measuring the impedance signal of the micro electrode and analyzing the results.Finally,the experimental results verify the feasibility of the micro nano sensor system.