Of the numerous applications in the life sciences, fluorescence detection is where our sensors excel. In fluorescence microscopy of tissues and cells and automated sequencing of DNA, by labeling or tagging antibodies or DNA molecules, the fluorescent label is excited by a UV source, and the identity of the base terminating the molecule is identified by the wavelength of the emitted light. Many biological molecules have an intrinsic fluorescence that can sometimes be used without attaching a chemical tag. These systems use high-intensity light sources to excite fluorescence from samples under observation, optically filtered, and then detected by a silicon photodiode.
Other life science applications include flow cytometry, blood chemistry, and food analysis. In the latter application, light reflectance is spectroscopically measured from many types of chemicals such as sugar, protein, water, and fat. The same wavelengths are also utilized for high-speed grain sorting. UV excited fluorescence also provides a method for detecting the presence of carcinogenic and bio-contamination.