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Modeling and Simulation Analysis of TFET-Based Devices for Biosensor Applications
Published in Balwinder Raj, Brij B. Gupta, Jeetendra Singh, Advanced Circuits and Systems for Healthcare and Security Applications, 2023
Semiconductor devices are tremendously used to build biosensors as they are abundantly available, susceptible, reliable, fast, and trim. ISFET (ion sensitive field effect transistor) is a typical semiconductor biotransducer. Still, it has few limitations, such as long-term hysteresis, external noise, intrinsic noise, and low recognition ability towards neutral analytes. To overcome these problems, DMFET (dielectric modulated field effect transistor) was introduced. DMFET can detect charged and uncharged analytes, but short channel effects are still present due to miniaturization [13]. To reduce SCEs and increase sensitivity, DM-GUD-TFET (dielectric modulated gate underlap doping less tunnel field effect transistor) biosensor is proposed. TFET is a semiconductor device that is like MOSFET but uses quantum tunneling for conduction. DM-GUD-TFET biosensor is a label-free sensor. Label-free sensors have high specificity and sensitivity; only one reagent is sufficient for the analysis; therefore, the cost and analysis time are reduced compared to the labeled methodology [14]. Immobilization of the target biomolecules is carried out to stabilize the biomolecule such that it is coupled to the bioreceptor, and the sensing process is initiated. Various immobilization methods are adsorption, covalent binding, cross-linking, and entrapment. Adsorption is most widely used for the label-free method.
Potentiometry: pH and Ion-Selective Electrodes
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
Ronita L. Marple, William R. LaCourse
Ion-selective field-effect transistors (ISFETs) are semiconductor devices used for measuring ionic species in solution. The device consists of a gate insulator, a drain, a source, a substrate, and a reference electrode. The gate is covered with an insulating layer of silicon nitride (Si3N4), and it is in contact with the test solution, which is also in contact with the reference electrode. The silicon nitride adsorbs ions of interest in its available sites. A variation in the concentration of the ions of interest in the test solution will change the concentration of adsorbed ions, varying the voltage between the gate and the source, and thus changing the conductivity of the channel of the ISFET. This conductivity is monitored electronically, providing a signal that is proportional to the logarithm of the concentration of ions of interest in solution (Skoog et al., 1998b, pp. 606–607). Figure 16.9 depicts an ISFET sensitive to hydronium ions in solution.
Analytical Design of FET-Based Biosensors
Published in Suman Lata Tripathi, Sobhit Saxena, Sushanta Kumar Mohapatra, Advanced VLSI Design and Testability Issues, 2020
Khuraijam Nelson Singh, Pranab Kishore Dutta
Ion-sensitive FET (ISFET) is based on the conversion of the ionic concentration of an electrolyte into an electrical signal. The detection of the analyte does not affect the chemical composition of the electrolyte, as there is not an actual transfer of charge in the whole process. The change due to the electrolyte only appears in the form of change in gate capacitance. In the beginning, ISFET was generally used for pH sensing; later, it was used for glucose monitoring, penicillin G determination, etc. [15,16].
Review of pH sensing materials from macro- to nano-scale: Recent developments and examples of seawater applications
Published in Critical Reviews in Environmental Science and Technology, 2022
Roberto Avolio, Anita Grozdanov, Maurizio Avella, John Barton, Mariacristina Cocca, Francesca De Falco, Aleksandar T. Dimitrov, Maria Emanuela Errico, Pablo Fanjul-Bolado, Gennaro Gentile, Perica Paunovic, Alberto Ribotti, Paolo Magni
ISFET pH sensors exploit a mature (more than 20 years) technology and have been used extensively for industrial, clinical and environmental pH monitoring as they offer a number of advantages, relative to glass electrodes. First, the sensor can be fabricated with conventional silicon based semiconductor technologies at reduced costs and ease of integration with electronic devices. Furthermore, it is small, resistant to mechanical shock and does not need a storage solution. Due to the different structure, the impedance of ISFET devices is lower with respect to glass electrodes, which has a beneficial effect on noise and stability. Commercially available sensors based on ISFET technology have been tested at sea with encouraging results and devices specifically designed for oceanographic research, mainly based on the Honeywell Durafet™ sensor, are currently used by research institutions (Johnson et al., 2016; Saba et al., 2019).
Characterisation of a Schottky ISFET as Hg-MOSFET and as cytochrome P450-ENFET
Published in International Journal of Electronics, 2018
Chinmayee Hazarika, Dhrubajyoti Sarma, Sujan Neroula, Kritanjali Das, Tapas Medhi, Santanu Sharma
ISFET is a chemical sensor that belongs to the FET family. Threshold voltage is an important parameter of these FET devices as it is the voltage at which the device starts conducting. The insulator layer of an ISFET device consists of surface groups, which when in contact with the electrolyte results into active sites. Exchange of protons between these sites and the ions in the electrolyte brings about a change in the charges at the insulator/electrolyte interface. These charges affect the threshold voltage of the device. The threshold voltage of an ISFET device is expressed as (Grattarola & Massobrio, 1998)