Directly sensing ISFET

Ion Sensitive Field-Effect Transistors (ISFETs) developed to measure pH and to sense a variety of analytes in solution are well known in the silicon technology field [11]. In these devices the gate insulator is in direct contact with the electrolyte solution (see Fig. 6.1). 

Ion-Sensitive Field-Effect Transistor (ISFET)-based Flow Velocity Sensor. The ISFET-based flow velocity sensor functions as a flow direction and diffusion coefficient detection device [ 10]. It senses the velocity of liquid through detection of ions. The sensor is shown in Fig. 8. It shows a chemical sensor-actuator system having one ion generator and one detector. The generator-detector pair detects ions that are electrochemically generated. Positive... 

An acetylcholine receptor may be immobilized in the place of the antibody on the ISFET. In the presence of the positively-charged acetylcholine, the potential difference between the sensing element and that of a reference ISFET (REFET) without a receptor changes in the same direction, indicating that the acetylcholine is strongly bound to its receptor. This is not the case for other proteins (catalase or BS A) when they are fixed in the place of the acetylcholine receptor. 

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