Transducers are the physical components of the sensor that respond to the products of the biosensing process and outputs the response in a form that can be amplified, stored, or displayed. The purpose of this article is to provide a summary of the main fundamental concepts involved, technological variations, applications, and challenges. As shown in Figure 1, biosensing occurs only when the analyte is recognized specifically by the biological element. It should be pointed out that some antibodies have been demonstrated to possess catalytic activities. These are also the desirable characteristics in an ideal biosensor.
Most commercial devices use enzymes as the biological recognition element.
For a given analyte-recognition element reaction, several transduction schemes may be applicable. However, constraints may be imposed by the intended use. The most common transduction parameters and corresponding device types are summarized in Figure 2. Amperometric devices detect changes in current as constant potential. Conductimetric devices detect changes in conductivity between two electrodes.