The use of Charge Coupled Device (CCD) detectors as an integral part of a biosensing system has become widespread in recent years due to several advantages of this type of detection, such as the ability to image multiple zones on the sensor, the flexibility of defining the sensing configuration and the low-noise performance of the detectors. The specification of the CCD as well as the selection of the other components in this system--including the source and the filters--is driven by the particular transduction mechanism, but all parts must be matched. Particular attention must be paid to reducing the various noise components of the CCD to obtain the lowest detection level, and it is shown that cooling the CCD is often a wise choice.