Note that VTH for an n-channel (p-channel) FET is positive (negative).With these properties, the FET can be configured as a biosensor by modifying the gate terminal with molecular receptors or ion-selective membranes for the analyte of interest. Tenatoprazole? The binding of a charged biomolecule results in depletion or accumulation Inhibitors,Modulators,Libraries of carriers caused by change of electric charges on the gate terminal. The dependence of the channel conductance on gate voltage makes FETs good candidates for electrical biosensors because the electric field generating from the binding of a charged biomolecule to the gate is analogous to applying a voltage to a gate.
In general, the drain current of the FET-type biosensor is defined as follows:IDS=1/2��CW/L(VGS?TTH)2?????at saturation region?(VDS��VGS?VTH)(1)IDS=��CW/L[(VGS?TTH)VDS?1/2V2DS]?at triode region?(VDS ISFET is similar to IGFET, but in the ISFET, the metal gate is replaced by an ion-selective membrane, electrolyte and a reference electrode (Figure 1). In the case of an ISFET biosensor, the amount of the current flow will be not only determined by the Inhibitors,Modulators,Libraries charges of biomolecules interacting on the gate dielectric, but also sensitive to pH, different ions, products of enzyme reactions, etc. An attractive feature of such FETs is that it is possible to detect biomolecular interactions in a label-free manner through a direct change in conductance or a related electrical property.Figure 1.Structure of ISFET. It consists of source, drain, gate insulator, and reference electrode.3.?Applications of ISFET BiosensorsOne 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 [6,7]. In this regard, Anacetrapib an ISFET device of small size Temsirolimus purchase 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.