Abstract: The present invention relates to a process for the detection of an analyte in a sample, comprising a) bringing the sample into contact with a first ligand which binds specifically to the analyte and which is immobilized on a substrate, and b) prior to or subsequent to step (a), bringing the sample into contact with a second ligand which binds specifically to the analyte and which includes a label: wherein the substrate comprises a holographic sensor comprising a support medium having a hologram disposed therein or thereon and the label causes an optical property of the sensor to change by interaction of the sensor with the label or, following the additional step of contacting the substrate with a reagent, by interaction of the sensor with a species produced by reaction of the label with the reagent, thereby indicating the presence of bound analyte.

Abstract: A grating-based sensor is disclosed that has a grating structure constructed and designed for both evanescent resonance (ER) fluorescence detection and label-free detection applications. Some embodiments are disclosed which are optimized for ER detection in an air mode, in which the sample is dry. Other embodiments are optimized for ER detection in liquid mode, in which the sample is suspended in liquid medium such as water. One and two-dimensional gratings are also disclosed, including gratings characterized by unit cells with central posts, central holes, and two-level, two-dimensional gratings. A readout system for such sensors is also disclosed. One embodiment includes a first light source optimized for collecting label-free detection data, a second light source optimized for collecting ER fluorescence amplification data, and at least one detector. In one embodiment, the detector is an imaging system and includes a CCD camera for collecting both ER and label-free data.