Requirements for proper sensor performance

For a given flow-through (bio)chemical sensor to be useful for solving real analytical problems, it must meet the indispensable or desirable requirements discussed in Chapter 1. One should bear in mind that many reported (bio)chemical sensors have some deterrent shortcomings (e.g. a slow response, a high sophistication, irreversibility, too short duration, irreproducibility, ease of contamination) that make them useless for routine applications in practice. Flow-through sensors should therefore meet four essential requirements for proper performance, namely  

The above four requirements vary somehow with the type of flowthrough sensor and detection system used. There are other, specific requisites, discussion of which is beyond the scope of this introductory chapter. A more detailed description of the optimal operational conditions for flow-through sensors is provided in subsequent chapters. 

Flow-through sensors based on integrated reaction and detection 

Flow-through sensors integrating detection and a chemical or biochemical reaction rely on immobilization in the probe proper or the flow-cell (or a special housing included in it) of a species intended to take part in or catalyse the reaction by which the analyte, viz. the catalyst or reagent, is measured, according to which the sensors described in this Chapter are divided into two broad categories. 

Unlike sensors based on an immobilized catalyst, those using an immobilized reagent can be classified according to whether the reagent is consumed (Section 3.4.1) or regenerated in the process (Section 3.4.2). 

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