Spectrophotometry and Optical Biosensor

Abstract

In the previous chapter we learned about optoelectronic light sensors, especially photodiode. Although many photodiodes are made to be specifically sensitive to a certain range of colors, e.g., UV-blue, red-IR, etc., they cannot tell the exact color or color combination of light signal. Photodiodes (and most other optoelectronic light sensors) simply inform us the intensity of light signals. Detailed information on color combination can be obtained by using a technique known as spectrophotometry, which involves an instrument spectrophotometer. Spectrophotometers are quite bulky and relatively expensive and have not been considered as a topic for sensors or biosensors. Recent years, however, very small spectrophotometers (a size comparable to a mobile phone) have become commercially available. In addition, spectrophotometers are becoming an integral part of many sensor and biosensor devices.