One distinct merit of the semiconductor-based biosensors like ISFETs, as opposed to optical systems, is their suitability for use in miniaturized measurement systems, thereby allowing its easy integration into the required electronics. In this regard, an ISFET device of small size and low weight might be appropriate for use in a portable monitoring system, i.e., a hand-held drug monitoring system. When it comes to sensitivity and specificity of biosensor, both the fabrication of a nano-scale device and elimination of nonspecific molecular adsorption would contribute to an improvement in the limit-of-detection (LOD) and selectivity of the biosensor.
Investigators have conducted extensive studies in the electronic analysis of biomolecules by monitoring the variations in the charge density using ISFETs. Currently, various kinds of biorecognition materials for biological analysis such as DNA, proteins, enzymes, and cells are being applied to ISFET measurements owing to the unique electrical and biological properties, thereby elevating the sensitivity and specificity of detection. Among a variety of types of biosensors, one of the most promising approaches and the focus of investigators’ concerns is the ISFET-based biosensors and their integration in biological components. In the ISFET system based on different biocontents for biological analysis, assorted concepts of biosensors like enzyme FETs, Immuno FETs, and DNA FETs that contain layers of immobilized enzymes, antibodies, and DNA strands respectively, have been reported in a large number of documents.