Flow-through sensors classifications

Figure 1.14 — Classification of flow-through sensors according to external shape. SMZ sensing microzone D detector W waste. For details, see text.

The classifications of sensors established in Chapter 1 can be used as guidelines to define various technical categories of flow-through sensors (Fig. 2.4). 

One possible classification is based on the type of physico-chemical phenomena that may occur in the sensor. Based on this criterion, there are passive flow-through sensors, which posses no reactive microzone and are... 

One other, very descriptive classification of flow-through sensors is based on the location of the active microzone and its relationship to the detector. Thus, the microzone can be connected (Figs 2.6. A and 2.6.B) or integrated (Fig. 2.6.C) with the measuring instrument. Sensors of the former type use optical or electric connections and are in fact probe sensors incorporated into flow-cells of continuous analytical systems they can be of two types depending on whether the active microzone is located at the probe end (e.g. see [17]) or is built into the flow-cell (e.g. see [18]) — in this latter case. 

Figure 2.6 — Classification of flow-through sensors according to the location of the active microzone relative to the measuring instrument (A,B) connected (C) built-in. (Reproduced from [1] with permission of the Royal Society of Chemistry).

Other possible classifications of flow-through sensors have been excluded from Fig. 2.4 because they are either of little consequence or dealt with in other sections below. Such is the case with the classification based on whether one or more of the active reaction ingredients (analyte, reagent, catalyst, reaction product) is immobilized temporarily or permanently on the active microzone. In addition, the immobilization process may involve one or several active components. 

Figure 5.2 — Classification of (bio)chemical flow-through sensors based on integrated reaction, separation and detection according to the type of separation technique involved.

Figure 2.4 — Classifications of flow-through (bio)chemical sensors.

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