Interferometric label-free biomolecular detection system

This work presents a simple evanescent wave sensing system based on an interferometric approach, suitable to meet the requirements of label-free sensor systems for detecting biomolecular interactions. It represents a basic concept towards label-free detection systems in various applications. The basic objectives of transducers for evanescent wave sensing are discussed. An optical detection system based on a interferometric approach using Young's double slit configuration is discussed, set-up and characterized. With refractometric measurements of various sucrose dilutions, the performance of the pure optical set-up is evaluated. A mean resolution of the effective refractive index of 3 sigma((Delta n) over barn(eff)) = 0.9 x 10(-6) without averaging was obtained and a reproducibility below sigma(r)(n(eff)) = 0.1 x 10(-6) was achieved. Furthermore basic experiments were carried out, for proofing the concept's suitability as a highly sensitive biosensor by detecting the hybridization of 21-mer DNA with an immobilized counterpart on the surface.