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 in the form of an imaging
system and includes a
CCD camera for collecting both ER and
label-free data. In other embodiments, the at least one
detector takes the form of a
spectrometer for collection of label-free data and a
photomultiplier for collecting ER data. In other embodiments, a single
light source such as a
tunable laser or
broad band light source is used.