Research On Digital Image Detection Technology Of Porous Silicon Biosensor

Porous silicon is a kind of nanostructured material.Because of its large specific surface area,easy to modify by biomolecules and adjustable refractive index,it can be made into a variety of biosensors.In this paper,the digital image detection technology of porous silicon biosensor is studied.In this study,the average gray value of the images before and after the biological reaction in the Bragg reflector was calculated to characterize the concentration of the measured molecules.This technology has the advantages of high sensitivity,short detection cycle,low cost,convenient and fast use.The main contents of this paper are as follows:Firstly,a bioassay technique for digital images of porous silicon transmission light based on the Structure of Prague is proposed.The technology uses infrared laser located at the edge of the band gap of Bragg mirror as the probe light,and incident to the porous silicon surface before and after DNA hybridization.The transmitted light is converted into visible fluorescence by laser viewing card,and then the fluorescent image is received by a digital microscope.The average gray value of the image before and after noise removal is calculated respectively,and the relationship between the image and the measured DNA molecular concentration is obtained.Secondly,the bioassay technology of transmitted optical image using mobile phone as a light detector is proposed.The detection method converts the detected light generated by the laser at the edge of the Prague reflector band,the incident to the porous silicon surface before and after the DNA hybrid reaction,the infrared observation card converts the transmitted light into visible fluorescence,and receives the fluorescent image by the mobile phone,calculates the average grayscale value of the image,and obtains the change relationship between the grayscale value of the image detected by the mobile phone and the concentration of the DNA molecule under test.The experimental results show that the detection limit of DNA molecules obtained by the transmission light image detection using mobile phones is n M level.Finally,the biological detection method of fluorescent image using mobile phone as light detector is proposed.The method connects the semiconductor quantum dot(Cd Se/Zn S)to the probe DNA and then modifies the products of the two into the holes in the porous silicon Bragg mirror of the conjoined target DNA.The resulting fluorescent image is recorded by the mobile phone by the excitation light generated by the semiconductor laser(375 nm)and the change of the target DNA concentration and its average grayscale value by calculating the average grayscale value of the fluorescent image.The experimental results show that the detection limit of DNA molecules obtained by fluorescence detection using mobile phones is p M grade.