Biosensing with one-dimensional photonic bandgap structure

Abstract

The optical properties of photonic bandgap (PBG) structures are highly sensitive to the geometry and refractive index. This makes PBG structures a good host for sensor applications. The binding of target species inside the PBG structure changes the refractive index of the material, which can be detected by monitoring the optical response of the device. One-dimensional PBG biosensors based on porous silicon (PSi) have been fabricated. The device is a microcavity, made of a symmetry breaking PSi layer (defect layer) inserted between two PSi Bragg mirrors. Narrow resonances are introduced in the photoluminescence and reflectance spectra. The large internal surface of the sensor is functionalized for the capture of target biological materials. When the sensor is exposed to the target, binding to the internal surface increases the effective optical thickness of the microcavity and thus causes a red shift of the optical spectrum. The sensor's sensitivity is determined by the morphology and geometry of the device. We will present the details of the materials science, sensor fabrication and optimization, and also describe experiments performed with biological targets.