After discussing the features of a differential ISFET/REFET measuring concept, the published attempts to construct a proper REFET are summarized. It is concluded that the present REFETs are based upon the addition of a blocking polymeric layer to the gate surface of an ISFET, but that this approach fails with respect to the required insensitivity to ionic strength variations as well as with res...

Since Ion Sensitive Field Effect Transistors (ISFETs) were introduced by Bergveld in 1970, much effort is put into new and improved materials for device optimization and sensitivity enhancement [1]. ISFET based biosensors have a fast response, are suitable for miniaturization and arrays can be made for simultaneous measurement of various parameters. Actually, ISFET device production relies on s...

Introduced as a tool for electrophysiology three and a half decades ago, the ion-sensitive field-effect transistor (ISFET) is a generic electrochemical structure offering a family of analytical devices for applications in agriculture, food processing, medical diagnostics, pharmaceuticals, paper, pulp and chemical industries, and environmental control. Besides its use as a chemical sensor, this ...

The conventional ion senwtlve sensors, such as glass membrane electrodes, coated unre electrodes, metal-metal oxide electrodes, etc , convert a non-electrical quantity mto an electrical quantity, which can then be measured wrth approplnate electronic clrcultry connected m senes Unpredictable devlatlons m transducer parameters cannot be controlled m such a measunng system Because the ISFET also ...

Intraluminal pH monitoring in man should be performed with disposable multichannel assemblies that allow recordings at multiple sites and prevent transmission of infection. Currently available glass electrodes are unsuitable for this purpose because of their size and price. We have thus constructed and tested a small, combined ion sensitive field effect transistor (ISFET) pH electrode incorpora...

Successful implementation of site-specific crop management relies on accurate quantification of spatial variation of important factors. Data collection on a finer spatial resolution than is feasible with manual and/or laboratory methods is often required but cost prohibitive. Therefore, there is a need for the development of sensors to more accurately characterize within-field variability. The ...

A new configuration realizing water quality monitoring device using ISFET involving low power CMOS Integrated “Ion Sensitive Field Effect transistor (ISFET)—Operational Amplifier is presented. The study’s main focus is on simulation of power and performance analysis of ISFET device, which is used for water quality monitoring. This approach can improve calibration of device to a fairly wide rang...

We propose to detect the charge redistribution of an antibody-antigen complex (a precipitate), formed in a layer on top of an ISFET, by means of a.c. measurements. In fact an increased specific conductivity of the precipitate is detected, caused by the amount of counterions, which is related to the fixed protein charge in the precipitate. We observed that an HSA-antiHSA immune complex, deposite...

A bioelectronic hybrid system for the detection of acetylcholine esterase (AChE) catalytic activity was assembled by way of immobilizing the enzyme to the gate surface of an ion-sensitive field-effect transistor (ISFET). Photometric methods used to characterize bonded enzyme and linker layers on silicon substrates confirm the existence of a stable amino-cyanurate containing AChE monolayer. The ...

A method for correction of threshold voltage drift in pH-sensitive ion-selective field effect transistors (ISFET’s) is presented. The proposed method allows accurate continuous monitoring of pH under clinical conditions corresponding to rapid pH changes such as those encountered in acute metabolic acidosis and cardiopulmonary bypass operations. This method, which involves monitoring the differe...