In this work, both the static and dynamic behaviors as well as the signal read-out circuits of ISFETs were studied. The standard NMOS structure in conjunction with the insulator-electrolyte capacitor was used to model the ISFET under study. The site-binding theory was incorporated to describe the chemistry occurring at the insulator/electrolyte interface. The mechanism of the threshold voltage ...

The sensitivity of conventional ion-sensitive field-effect transistors is limited to the Nernst limit (59.14 mV/pH). In this study, we developed a pH sensor platform based on coplanar gate AlGaN/GaN metal-oxide-semiconductor (MOS) high electron mobility transistor (HEMT) using resistive coupling effect overcome limit. For coupling, comprising control (CG) and sensing (SG) was designed. We inves...

We report the integration of inorganic nanotubes into metal-oxide-solution field effect transistors (FETs) which exhibit rapid field effect modulation of ionic conductance. Surface functionalization, analogous to doping in semiconductors, can switch the nanofluidic transistors from p-type to ambipolar and n-type field effect transistors. Transient study reveals the kinetics of field effect modu...

We have investigated the effect of deoxyribonucleic acid (DNA) adsorption on a graphene field-effect-transistor (FET) device. We have used graphene which is grown on a Ni substrate by chemical vapour deposition. The Raman spectra of our graphene indicate its high quality, and also show that it consists of only a few layers. The current-voltage characteristics of our bare graphene strip FET show...

The operation of a pH (Hþ ion concentration) sensitive ion-sensitive field-effect transistor (ISFET) microsystem with a sensitivity of 40– 45 mV=pH is demonstrated. This system has two identical ISFETs as the inputs to a pair of ISFET operational transconductance amplifiers (IOTAs) arranged in a novel differential architecture. The IOTAs have different sized p-MOSFET load transistors that enabl...

Ion sensitive field-effect transistor (ISFET) based urease biosensors with solid state reference systems for single-ended and two-ended differential readout electronics were investigated. The sensing membranes of the biosensors were fabricated with urease immobilized in a conducting polymer-based matrix. The responses of 12.9∼198.1 mV for the urea concentrations of 8∼240 mg/dL reveal that the a...

A silicone ladder-type polymer was successfully utilized for a matrix of an ion sensing membrane to fabricate an ion-sensitive field-effect transistor. An ion sensing membrane was readily fabricated by mixing a silicone ladder-type oligomer with a quaternary ammonium salt, casting onto the gate of the field-effect transistor, and polymerizing with heating. Since no acid catalysts were needed to...