Chapter 1
What are Chemical Sensors?
1.1 Chemical Sensors: Definition and Components
The definition of an electrochemical biosensors given in ref. [1] can be adapted slightly to provide a general definition of the chemical sensor as follows. A chemical sensor is a self-contained device that is capable of providing real-time analytical information about a test sample. By chemical information we understand here the concentration of one or more chemical species in the sample. A target species is commonly termed the analyte or determinand. Besides chemical species, micro-organisms and viruses can be traced by means of specific biocompounds such their nucleic acid or membrane components. Physical sensors are devices used to measure physical quantities such as force, pressure, temperature, speed, and many others.
The first (and also best known) chemical sensor is the glass electrode for pH determination, which indicates the activity of the hydrogen ion in a solution.
When operated, a chemical sensor performs two functions, recognition and transduction, which are exemplified by the allegory in Figure 1.1. First, the analyte interacts in a more or less selective way with the recognition (or sensing) element, which shows affinity for the analyte. The sensing element may be composed of distinct molecular units called recognition receptors. Alternatively, the recognition element can be a material that includes in its composition certain recognition sites. Beyond this, the recognition element ...
