Research on Photonic Crystal–Based Biosensor for Detection of Escherichia coli Colony

In this paper, a biosensor based on 1D-PhC (one-dimensional photonic crystal) is proposed for detecting colony of E. coli (Escherichia coli) by analyzing the volume fraction of E. coli in analyte. The performance of the biosensor is evaluated by FDTD (finite-difference time-domain) method, and the parameters of the biosensor are optimized by orthogonal experiments. The simulation results show that the optimum parameters of the biosensor are A1B5C5D4E5 with the FOM (figure of merit) and S (sensitivity) of 125 and 174a nm/RIU, respectively. The center wavelength is the major factor affecting the performance of the biosensor. The S and FWHM (full width at half maximum) of the sensor are increased with the increasing of the center wavelength. In addition, the effective refractive index of the analyte at different volume fractions of E. coli is calculated by the Bruggeman model. The volume fraction of E. coli in the analyte is positively correlated with the resonance wavelength shift of the biosensor, and the linear correlation coefficient is 0.996. Therefore, it is feasible to detect the number of E. coli in the analyte by the resonance wavelength shift of the biosensor.