The ion-sensitive field effect transistor (ISFET) of chemical sensors has been used due to many reasons which have the advantages of small size, light weight and fast response by semiconductor processing. In recently, the sensing membranes applied to high-k materials such as Al2O3, ZrO2, HfO2, TiO2 and Ta2O5 for pH-ISFET were investigated because of the high sensitivity [1]. The Al2O3 film amon...

A number of potentiometric biosensors based on coimmobilization of enzymes with different types of zeolite on pH-ion-sensitive field-effect transistor (ISFET) have been developed. Their working characteristics have been determined and compared. It was shown that clinoptilolite and zeolite Beta polymorph A (BEA) are more promising for creating biosensors than zeolite A. Changing the concentratio...

The Field Effect sensors are broadly used for detecting various target analytes in chemical and biological solutions. We report the conditions under which the pH sensitivity of an Ion Sensitive Field Effect transistor (ISFET) sensor can be significantly enhanced. Our theory and simulations show that by using pH buffer solutions containing counter-ions that are beyond a specific size, the sensor...

A pH sensor fabricated on a single chip by an unmodified, commercial 0.6m CMOS process is presented. The sensor comprises a circuit for making differential measurements between an ion-sensitive field-effect transistor (ISFET) and a reference FET (REFET). The ISFET has a floating-gate structure and uses the silicon nitride passivation layer as a pH-sensitive insulator. As fabricated, it has a la...

By performing an acid-base titration by coulometric generation of OHor H+ ions at an inert electrode in close proximity to the pH-sensitive gate of an ISFET, it is possible to determine the acid or base concentration of a solution using the ISFET as an indicator device for the equivalence point in the titration curve. Typical values for the titration time are 0.1 to 10 s for acid or base concen...

The electrochemical detection of interactions between aptamers and low-molecular-weight targets often lacks sensitivity. Signal amplification improves the detection of the aptamer-analyte complex; Bsm DNA polymerase was used to amplify the signal from the interaction of vanillin and its aptamer named Van_74 on an ion-sensitive field-effect transistor (ISFET)-based biosensor. The aptamer was imm...

The development of ChemFET-based sensors for the soil analysis nitrogen-based ions is described in this work. Focusing on fluoropolysiloxane (FPSX) polymer-based matrix, nonactin and tetradodecylammonium nitrate (TDDAN) were shown to have best properties detection ammonium NH4+ NO3- respectively. Thus, FPSX-based pNH4-ISFET pNO3-ISFET microsensors exhibited good (sensitivity around 56 mV/pX con...

The paper presents a novel readout configuration for ISFET sensors based on Wheatstone-Bridge connection. This design technique allows on-chip integration, temperature compensation and measurements from ISFET/REFET pairs. The circuit is capable of operating in differential mode, and can also perform common mode and combined measurements, while improving the immunity to noise and interferences. ...

The proper design and simulation of modern electronic microsystems oriented towards environment monitoring requires accurate models of various ambient sensors. In particular, this paper presents a comprehensive model of an ion sensitive field effect transistor (ISFET). The model can be employed straightforwardly for simulations at device, circuit or system level. First, the model was validated ...