General features of bio chemical sensors

The first group of sensor properties in Fig. 1.15 is concerned with the quality of results obtained in analytical processes involving a (bio)chemical sensor. All of them are obvious targets of analytical tasks [3]. As shown in the following section, the accuracy of the analytical results relies on a high reproducibility or repeatability, a steep slope of the calibration curve (or a low detection or quantification limit) and the absence of physical, chemical and physico-chemical interferences from the sample matrix. Sensors should ideally meet these essential requisites. Otherwise, they should be discarded for routine analytical use however great their academic interest may be. 

The second group of properties is concerned with sensor operation in general and the peculiarities of the recognition element in particular. Ideally, a sensor should be fully reversible. Otherwise, it should lend itself readily to rapid, effective, reliable regeneration in order to be actually reusable. If 

Other interesting properties of (bio)chemical sensors are related to their effectiveness for solving real analytical problems. First, these analytical devices should be easy to construct, operate and preserve. Ruggedness, defined here as the confidence that small variations in the experimental conditions (pH, temperature, ionic strength, pressure) will not alter the sensor functioning or response, is very important. A low cost is also desirable, particularly with single-use (bio)chemical sensors. 

Compatibility between sensors and automatic and automated analytical systems is crucial as it allows two Analytical Chemistry trends to be combined (see Fig. 1.1). Probe-type and planar sensors can be used in automated batch systems including robot stations, as well as in continuous (mixed in-line/on-line) systems. On the other hand, flow-through sensors are only compatible with continuous configurations. 

As noted earlier, on-line process monitoring is among the application areas that can benefit most from the use of sensors provided they can be incorporated into portable systems. Electrochemical sensors are generally more suitable for these applications, even though optical sensors can also be readily adapted for this purpose (e.g. by using LEDs or photodetectors instead of conventional photometers) at the expense of somewhat degraded spectral resolution and sensitivity. 

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