SnO2 extended gate field-effect transistor as pH sensor

Abstract

Extended gate fi eld-effect transistor (EGFET) is a device composed of a conventional ion-sensitive electrode and a MOSFET device, which can be applied to the measurement of ion content in a solution. This structure has a lot of advantages as compared to the Ion-Sensitive Field Effect Transistor (ISFET). In this work, we constructed an EGFET by connecting the sensing structure fabricated with SnO 2 to a commercial MOSFET (CD4007UB). From the numerical simulation of site binding model it is possible to determine some of the desirable characteristics of the fi lms. We investigate and compare SnO 2 fi lms prepared using both the Sol-gel and the Pechini methods. The aim is an amorphous material for the EGFET. The SnO 2 powder was obtained at different calcinating temperatures (200 -500 0 C) and they were investigated by X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The fi lms were investigated as pH sensors (range 2-11).

Mechanisms of Ion Detection for FET-Sensors Using FTO: Role of Cleaning Process, pH Sequence and Electrical Resistivity

“…Therefore, the majority of works using EGFET as part of a sensor describes it as a pH-sensor 3,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] . PH monitoring and control, for itself, are quite important.…”

Effects of Measurements Conditions on an Extended-Gate FET used as pH sensor

“…Bearing research and future technological applications in mind, a good strategy would be to replace ISFET with the extended-gate field-effect-transistor (EGFET), due to its possibility to isolate the sensitive layer from the electronic components. In EGFET, a conducting wire connects a commercial MOSFET to a sensitive layer 8 , and it is easy to replace the sensitive layer. Moreover, it is feasible to alter the measurement conditions without modifying the MOSFET conditions, as the light exposure of the extended gate and the temperature of the sensing film as well.…”

Comparative Sensibility Study of WO3 ph Sensor Using EGFET and Ciclic Voltammetry

“…Based on ISFET, Van Der Spiegel et al 4 , introduced another structure named Extended Gate Field Effect Transistor (EGFET) which has a more flexible shape compared to ISFET, and also presents better long-term stability, since the ions from the chemical environment are excluded from any region close to the FET gate insulator 5 . Recently, several thin films have been widely used as the sensing material of the EGFET pH sensors, such as carbon nanotubes 6 , SnO 2 [7] , ZnO [8] , V 2 O 5 xerogel 9 , V 2 O 5 /HDA [10] , V 2 O 5 /WO 3 [11] , V 2 O 5 /TiO 2 [12,13] . However, the search for improved materials as an alternative for ion-sensing membranes still remains in this field of study.…”