Highly Sensitive 1D Photonic Crystal Biosensor for Early Malaria Detection via Refractive Index.

This article presents a theoretical investigation of a highly sensitive one-dimensional photonic crystal (1D-PC) biosensor for early malaria detection using the Transfer Matrix Method (TMM). The proposed structure, Air/(PbS/SiO2)4/defect/(PbS/SiO2)4/substrate, is optimized by adjusting the defect layer thickness and incidence angle to enhance defect-mode resonance characteristics. The design enables strong resonant peaks and significant wavelength shifts at 1550 nm. The sensor operates over a refractive index range of 1.371-1.402 RIU, corresponding to different malaria infection stages. A maximum sensitivity of 977.74 nm/RIU and a quality factor of 93.8 × 103 are achieved at a defect thickness of 1.2da. Increasing the thickness to 1.4da improves sensitivity to 1163.22 nm/RIU with a quality factor of 82.57 × 103. The design also exhibits a low detection limit of ~10-6 RIU and a high figure of merit, indicating strong potential for rapid, accurate, and cost-effective malaria diagnosis.