pH and Procaine Sensing Characteristics of Extended-Gate Field-Effect Transistor Based on Indium Tin Oxide Glass

Abstract

The pH sensing properties of an extended-gate field-effect transistor (EGFET) based on indium tin oxide (ITO) glass are investigated in this study. The separating structures in the EGFET are examined using a current–voltage measurement system to measure I–V curves. A readout circuit is applied to measure the pH sensing EGFET output voltage, and nonideal factors (drift and hysteresis effects) are monitored in different buffer solutions (pH=1–11). It was found that separating structures for ITO glass sensors have a high pH sensitivity (∼55 mV/pH), a low drift rate and a small hysteresis width in the concentration range between pH=1 and 11 in buffer solutions. The EGFET was used in fabricating a drug-sensitive field-effect transistor (DrugFET) sensor for procaine hydrochloride. The DrugFET was prepared using a combination of the EGFET and a drug-sensitive membrane that measured the procaine concentration in the 1×10-2–1×10-6 mol/L range. The separating structure was used with a procaine DrugFET with a good response (∼200 s) at room temperature.

Melanin as an active layer in biosensors

“…Comparing with the literature for other materials, the sensitivity found is quite satisfactory. 1,3,5,[12][13][14] The sensitivities using gold substrates are always higher with respect to ITO. The main reason is probably due to its better conductivity.…”

“…[1][2][3][4][5][6] pH sensitive biosensors are extensively studied, since it has many applications, especially in the monitoring of biological systems such as blood, but also for chemical analysis and environment monitoring. [7][8][9][10][11] There are many options of materials that can be used as ion sensitive layers.…”

“…1,6,9 Recent studies shows that these sensors can have high sensitivities depending on the material used, like zinc oxide based sensors have sensitivity of 38 mV/pH, 1 tin oxide 56-58 mV/pH, 12 and indium tin oxide 55 mV/pH. 3 In the case of organic semiconductors, which are in general less used, nanostructured polyaniline and poly(vinylsulfonic acid) have a sensitivity of 58 mV/pH, 13 carbon nanotubes with 50.9 mV/pH, 5 and hibrid materials like vanadium oxide/hexadecylamine, 38.1 mV/pH. 14 The Site-Binding Model can describe the working mechanism of EGFETs.…”

Coaxial-structured ZnO/silicon nanowires extended-gate field-effect transistor as pH sensor

“…Recently, there were many studies introducing extended-gate field-effect transistor (EGFET) as an alternative for the fabrication of ISFET [2,3]. EGFET exhibited many advantages over the conventional ISFET, such as low cost, simpler packaging, temperature and light insensitivity, flexibility of shape of the extended-gate structure, and better long-term stability [4][5][6][7].…”

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

“…The development of the ISFET mimics a commercial Metal Oxide Semiconductor Field Transistor (MOSFET) in which the metal gate electrode is removed, in order to expose the underlying insulator layer to the solution. 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] .…”