Rearch On Laser Self Mixing Iinterference Detection System Based On Microfluidic Chip

The detection of single micro and nano particles is to explore the characteristics of single particles in the scale of nanometer to micron.It is used in medicine,environment,materials and other fields,and plays an important role in the micro research of related fields.However,the traditional detection method of single micro and nano particles has some limitations,which limits the wide application of single micro and nano particle detection.Therefore,the research of single micro and nano particle detection system plays an important role in promoting the detection of single micro and nano particles in various fields.In this paper,the laser self mixing interference detection system based on microfluidic chip is studied,and the feedback signal characteristics of a single micro nano particle are explored.A microfluidic chip suitable for focusing micro and nano particle sample solution is proposed,and the integration of microfluidic chip and laser self mixing interference detection system is realized.The micro and nano particles with different particle sizes are detected and analyzed respectively.The polystyrene particles of micron size are detected and counted one by one by collecting and analyzing the feedback signal characteristics,which provides a new idea for the detection of micro nano particles in various fields,and provides a convenient and integrated tool for the detection of single micro nano particles.It has practical significance.The main contents of the research include the following parts:(1)According to the particle size characteristics of microfluidics,the three-dimensional model and finite element analysis of microfluidics are completed.The microfluidics chip adopts the classic cross channel structure,which includes the sample inlet,sheath inlet and waste liquid outlet.The channel depth of microfluidics chip is 50 ? m and the width is 100 ? M.The experimental results show that the cross microfluidic chip has good focusing effect.(2)Based on the principle of laser self mixing interference,the detection of single micro nano particle is studied.Based on the Lang Kobayashi rate equation,the expression of the feedback signal of the laser self mixing interference detection of a single micro nano particle is obtained,and the output signals of different feedback levels are simulated.It is shown that the output waveform characteristics of the laser self mixing interference feedback signal of a single micro nano particle are similar In sine wave.(3)The signal processing platform of laser self mixing interference detection feedback signal is built.Based on PC-DAQ,the signal processing module is designed with the customized Lab VIEW and matlab program as the software platform,and the corresponding functional integrated circuit board is designed to realize the collection,storage,display and analysis of the laser self mixing interference feedback signal(4)A laser self mixing interference detection system based on microfluidic chip is built.According to the research purpose of this project,the Z-type microfluidic chip fixture is designed by using the corresponding mechanical devices.The fluid focusing module,the laser self mixing interference detection module and the external equipment are integrated to realize the integration of a single micro nano particle detection system and complete the overall construction of the system.(5)The system constructed in this paper is used to detect single micro nano particle and analyze the characteristics of laser self mixing feedback signal of single micro nano particle.In the experiment,four kinds of polystyrene microspheres with different particle sizes were used to detect the single micro nano particles.The feedback signal characteristics of four kinds of micro nano particles were analyzed from the time and frequency domain,and the relationship between the waveform characteristics of the feedback signal and the four kinds of micro nano particles was explored.The counting of micro nano particles was realized.The detection rate was 92.7%.