Research On One-dimensional Photonic Crystal Bioloical Sensors Based On Porous Silicon

Various optical detecting applications based on porous silicon (PS) have attracted a greatattention due to its remarkable optical properties and large functional surface area. PS, withits particular surface morphology, makes this material very suitable for many differentapplications in various fields.However, at present, the study of multilayered PS-based biosensors of various onedimensional PS structures are all based on the assumption that the smaller biologicalmolecules in the multilayered PS are distributed uniformly in each layer, while the realdistribution of the biological molecules in the multilayer structure of PS has not been reported.Whether biological molecules are distributed uniformly in each layer has very importantsignificance in the design and development of accurate multilayered PS-based biosensors.Therefore, in this paper, we contrast and analyze the distribution of the small biologicalmolecules in the PS microcavity biosensor from theory and experiment respectively. Thereflection spectral analysis technology and the transfer matrix theory are employed. It isfound that biological molecules in multilayered PS are not uniformly distributed in each layer,and it is difficult for these biological molecules to the bottom of the PS multilayer structure.Therefore, this research has much guiding significance in the practical design of commercialmultilayered PS-based biological sensors.We adopt the electrochemical etching methods to prepare a one-dimensional PSmicrocavity structure, then add APTES reagent and measure the spectral reflectance of theAPTES small molecules before and after entering fully into the PS microcavity. At the sametime, we compare the measurements with the theoretical simulation of the small moleculesentering into the PS microcavity. Through analysis of the spectrum, the study shows that evenif the size of biological molecules relative to PS aperture is small enough, biologicalmolecules in a multilayered PS are still not evenly distributed in each layer, and it is difficultfor these molecules to enter the bottom of the multilayered PS. The study also gives us a hintthat in the actual business development of biological sensors based on PS, we should try to use as few layers as possible.