A Biosensor Based on an Assembled Porous Silicon Microcavity

To solve the problem of the limited depth of penetration of biomolecules into silicon biosensors, which affects the performance of porous silicon devices, a new biological detection device assembled with porous silicon and Bragg structures is proposed that allows the biomolecules to directly enter the porous silicon microcavity layer, thus greatly shifting the resonance peak and improving the sensitivity of the porous silicon. The fabricated porous silicon devices with microcavities and Bragg structures are functionalized and coupled with biomolecules and then assembled with Bragg devices based on quartz glass to form the microcavity. Using the reflection spectrometer to detect the defect peak redshifts of different concentrations of target DNA molecules before and after reaction with the probe DNA molecules, obtaining the difference between the refractive indices before and after reaction. With an increase in the molecular concentration of the DNA in the target and an increase in the defect peak difference, the detection limit is 22.5 nM. The assembled microcavity has the advantages of high detection sensitivity, free labelling, low costs and so on.