Chapter 19
Optical Sensors – Applications
As indicated in the previous chapter, there are a broad range of optical transduction methods that allow the development of a great diversity of optical sensor platforms. In order to develop a particular kind of optical sensor, one has to select a suitable recognition method and integrate the recognition element with an appropriate optical sensor platform.
This chapter presents typical strategies for the development of optical sensors for various classes of applications focusing on recognition methods for particular kinds of analytes. Included are optical sensors for inorganic species, such as the hydrogen ion, metal ions, and certain gaseous compounds. Optical sensors based on enzymes, affinity recognition receptors, and nucleic acids are also presented.
19.1 Optical Sensors Based on Acid–Base Indicators
19.1.1 Optical pH Sensors
Optical pH sensors make use of acid–base indicators (also called pH indicators) that are organic compounds capable of undergoing acid dissociation accompanied by a change in color:
Symbols in square parentheses represent activities of pertinent species. The equilibrium constant in Equation (19.1) is the indicator constant. An absorbance measurement at the specific wavelength of each indicator form (
or ...
