Research On Microparticle Detection Technology Based On Optofluidic Lens-free Holographic Image

At present,it is very necessary to detect microparticles in many aspects of production and life,such as how to rapidly detect harmful micro-algae in ship ballast water,how to effectively and rapidly detect the internal components of oil in industrial production,and how to rapidly detect cancer cells in the field of clinical medicine,etc.Because the commonly used detection methods for detecting mocroparticles have the disadvantages of large volume,high price and complicated operation,so that it is very necessary to carry out rapid detection of microparticles.The technology based on optofluidic lens-free digital holographic imaging can obtain holographic images characterizing the characteristics of microparticles.Microparticles can be researched by extracting the characteristic information of holographic images,which has a very broad application prospect in marine transportation,industrial production and clinical medicine.The detection system and detection method of microparticles based on optofluidic lens-free digital holographic imaging was presented in this paper.The detection principle of the detection system was that the excited light from the light source passes through a small hole to reach the surface of the microparticles,the hologram was formed by mutual interference of light passing through the microparticles and light scattered by microparticles,and the holographic image was characterized to analyze,researching the characteristics of the microparticles.The microparticle detection system based on optofluidic lens-free holographic imaging designed in this paper was mainly composed of a light source module,a small through-hole module,a light propagation module,a stage module,an image acquisition module and an image processing module,which consisting of six parts.After the lens-free holographic image of the microparticles was acquired through the designed system,the experimental results of the lens-free holographic imaging were analyzed from two aspects:One was detection and analysis based on the original holographic image;the other was detection and analysis based on the lens-free holographic reconstructed image.Several indicators are selected in the holographic image of microparticles to characterize the microparticles.These indicators are the area of the central bright speckle,the average of gray values of central bright speckle,the area of the first dark stripe,the average of gray values of the first dark stripe and gray level difference value which is the difference between the average of gray values of central bright speckle and the average of gray values of the first dark stripe.According to these characteristic parameters,the characteristics of the micro-particles can be discriminated,such as identifying the activity of the microalgae cells,identifying the internal components of the oil droplets and identifying cancer cells.The method uses a microfluidic chip as a sample platform,and has the advantages of small device size and rapid detection.In this paper,the reconstruction of holographic images of microparticles is carried out by reconstruction algorithm for further analysis of microparticles,and the reconstructed images of the microparticles are obtained,which lays the foundation for the species identification of the microparticles.