Microfluidic Chip Based On Photonic Crystal And Research Of Its Application In Point-of-care Testing

Point-of-care testing（POCT）is a testing technology that can obtain the testing results on site and in comparably shorter time.POCT is free of specialized personnel and sophisticated facilities,which make it a critical thrust in the field of medical testing.POCT can promote the development of personalized and precision medication,and propel the of involvement of health and medical services in underdeveloped areas.However,there remain a series of critical challenges associated with POCT,including but not limited to:how to guarantee the sensitivity and accuracy of the testing while simplifying the device and equipment,the narrow measurement range of some analytes and the interference from the endogenous substances in clinical samples,and the higher cost compared to laboratory testing.This work is based on photonic crystal materials that’s capable of amplifying fluorescence intensity,and integrated it with microfluidics,which had been intensively applied in POCT,to present a microfluidic chip for fluoroimmunoassay.This work improved the present method from several aspects,making it more appealing for POCT.The detailed work is as follow:（1）this work introduced photonic crystal structure into nitrocellulose by using conventional nitrocellulose as starting material and photonic crystal templates obtained from the self-assembly of Si O₂ nanoparticles.The structure of the photonic crystal was adjusted to endow it with the optimized fluorescence amplification capability.By the patterned selective hydrophilic modification of the hydrophobic PDMS substrate,the patterned Si O₂ photonic crystal template was fabricated,leading to patterned photonic nitrocellulose.Patterned two-dimensional photonic nitrocellulose was fabricated by hot embossing.（2）PDMS microfluidic chip was fabricated by photolithography and soft lithography,and the integrated microfluidic chip was obtained by adhering the PDMS chip onto the patterned photonic nitrocellulose.This work leveraged the gas permeability of PDMS to solve the problem of liquid sample introduction,which was achieved by the degassing of PDMS to facilitate the self-introduction of liquid sample in the absence of external pumping equipment.（3）the microfluidic chip fabricated in this work was used for fluoroimmunoassay of 3 protein biomarkers.The conventional fluorescence microscopy was replaced by a3D-printed cartridge and the APP on a smartphone to rapidly read and analyse the fluorescence signal,which can promote its application in POCT.