Chapter 20a Optical sensors

Abstract

Publisher Summary This chapter shows a general schematic diagram of an optical sensor and detection instrumentation utilizing optical fibers. Optical fibers can guide the light from the light source to a remote distance without losing much of the light intensity. In most optical sensors, dual optical fibers are used; one is to guide the light from the source to the sensing site and the other to collect the detecting light back to the detector. Single fibers are also used in many designs. By using optical fiber bundles, remote and multiple sensing is possible. An optical sensor can be designed by utilizing the intrinsic property of certain analytes that interact with light. However, very often selectivity has to be improved by using a sensing mediator that reacts selectively with the analyte and generates an optical signal change. The most often used detection methods for the optical sensors are based on absorption, luminescence, reflectance, and Raman scattering measurements. The chapter presents the principal equations and the unique designs for optical sensors. Optical biosensors can be designed when a selective and fast bioreaction produces chemical species that can be determined by an optical sensor. Like the electrochemical sensors, enzymatic reactions that produce oxygen, ammonia, hydrogen peroxide, and protons can be utilized to fabricate optical sensors.