Detection principles of biological and chemical FET sensors.

The fabrication of pH-sensitive ISFET devices in an unmodified two-metal commercial CMOS technology (1.0 m from Atmel-ES2) is reported. The ISFET devices have a gate structure compatible with the CMOS process, with an electrically floating electrode consisting on polysilicon plus the two metals. The passivation oxynitride layer acts as the pH-sensitive material in contact with the liquid solution. The devices have shown good operating characteristics, with a 47 mV/pH response. The use of a commercial CMOS process allows the straightforward integration of signal-processing circuitry. An ISFET amplifier circuit has been integrated with the ISFET sensors.

/pdf/ion-sensitive-field-effect-transistors-fabricated-in-a-2n6s6be27r.pdf

Ion-sensitive field-effect transistors fabricated in a commercial cmos technology

Metal oxides based electrochemical pH sensors: Current progress and future perspectives

In this study, extended-gate field effect transistor (EGFET) was applied to fabricate disposable urea biosensor. And the 1.5 V low-voltage instrument amplifier was adopted to realize the portable urea biosensor. However, the difference between extended-gate field effect transistor and traditional ion-selective field effect transistor is the position of the sensitive membrane. The extended-gate field effect transistor was separated into two parts, which are the sensitive membrane and MOSFET. Hence, the MOSFET device can be designed to be a part of the readout circuit and the sensitive membrane was only put in the solution. Therefore, the configuration of the extended-gate field effect transistor can reduce the influence of the temperature, light and the erosion by the solutions. Besides, the configuration can reduce the cost substantially. The configuration of the extended-gate field effect transistor will raise the competitiveness to develop the disposable biosensor. The content of the urea in blood is one of the indexes to diagnose the renal efficiency. Then, the portable urea biosensor is the important expandable aspect. In this study, the gels, which are the poly vinyl alcohol with pendent styrylpyridinium groups, were used to immobilize the urease. The detection of the urea is based on the variation of pH value. Then, the dynamic range of the urea biosensor is from 0.31 to 120 mg/dl at the 5 mM phosphate buffer solution and the response time is about 2 min.

Portable urea biosensor based on the extended-gate field effect transistor

pH-sensing materials and configurations are rapidly evolving toward exciting new applications, especially those in biomedical applications. In this review, we highlight rapid progress in electrochemical pH sensors over the past decade (2008–2018) with an emphasis on key considerations, such as materials selection, system configurations, and testing protocols. In addition to recent progress in optical pH sensors, our main focus in this review is on electromechanical pH sensors due to their significant advances, especially in biomedical applications. We summarize developments of electrochemical pH sensors that by virtue of their optimized material chemistries (from metal oxides to polymers) and geometrical features (from thin films to quantum dots) enable their adoption in biomedical applications. We further present an overview of necessary sensing standards and protocols. Standards ensure the establishment of consistent protocols, facilitating collective understanding of results and building on the current...

D. Babic

Papers

The extended gate chemically sensitive field effect transistor as multi-species microprobe☆