Asymmetric optofluidic grating – a versatile platform for biosensing

The asymmetric nanofluidic grating detector to be presented in this thesis combines the advantages of an optical detection method with micro- and nanofluidics. This relatively new field of research referred to as optofluidics enables the sensitive detection of target molecules with low sample volumes and short transport paths. The sensing element consists of nanofluidic channels arranged as an optical grating. Optical path differences within reference and detection channels can be measured directly via an intensity ratio within the diffraction pattern that forms when the grating is illuminated by a laser beam. The measurement in the Fourier space is sensitive to a change in refractive index for instance due to the accumulation of target molecules in the functionalised grating channels. Importantly, the newly developed sensing technology works without labelling and the parallel arrangement of detection and reference channels allows the direct common mode rejection within the measurement itself. This thesis presents the basic concept, the design and mathematical model as well as the application of the asymmetric nanofluidic grating detector.