Electrical sensor response signals

In amperometry, we measure the electric current between a pair of electrodes that are driving an electrolysis reaction. One reactant is the intended analyte and the measured current is proportional to the concentration of analyte. The measurement of dissolved 02 with the Clark electrode in Box 17-1 is based on amperometry. Numerous biosensors also employ amperometry. Biosensors8-11 use biological components such as enzymes, antibodies, or DNA for highly selective response to one analyte. Biosensors can be based on any kind of analytical signal, but electrical and optical signals are most common. A different kind of sensor based on conductivity—the electronic nose —is described in Box 17-2 (page 360). 

The worst case is damping above the operational frequency. This means that the sensing element response includes a delay. For force and torque sensors there is no standard equipment on the market, as for electrical circuits. For signal transmission only radio-frequency based systems can avoid mechanical influences (Fig. 7.12.12). 

In contrast to the above-mentioned effects, which will enhance the sensor response, it is possible that an increased catalytic reaction on the electrode material with a direct desorption from there, will lead to a gas consumption, which is not monitored by the electrical readout. In consequence, this gas consumption may lead to an overall lowering of the analyte (depending on the given setup) and may thus even lead to a lowering of the sensor signal. 

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