Open AccessLow‐cost fabrication of indium tin oxide (ITO) FETs for sodium detection in electrolytes and human urine
Author(s) -
Gianti Mahmudah Salwa,
Oh Hong Gi,
Cho Hae Shin,
Jo Da Ae,
Indriatmoko Muhammad Naufal,
Lim Joon Mook,
Jang Byoung Kuk,
Song Kwang Soup
Publication year - 2021
Publication title -
electronics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.375
H-Index - 146
eISSN - 1350-911X
pISSN - 0013-5194
DOI - 10.1049/ell2.12228
Subject(s) - isfet , indium tin oxide , materials science , thin film transistor , sputtering , analytical chemistry (journal) , substrate (aquarium) , volumetric flow rate , indium , field effect transistor , optoelectronics , nanotechnology , thin film , chemistry , transistor , layer (electronics) , chromatography , electrical engineering , oceanography , physics , voltage , quantum mechanics , geology , engineering
Here, robust and low‐cost sodium sensors based on the ion‐sensitive field‐effect transistor (ISFET) are fabricated using indium tin oxide (ITO) thin film. The effect of the presence of oxygen during the sputtering of the ITO thin film is characterized on the sensitivity of sodium ion (Na + ) detection. A sodium ionophore III membrane is applied on the ITO substrate to fabricate ISFET (ITO‐ISFET). The results reveal that the increase in the oxygen gas flow rate (0–1 sccm) with a fixed argon flow rate at 20 sccm during sputtering increased the sensitivity of ITO‐ISFET to Na + from 15.8 to 100.9 mV/decade. In addition, the proper condition with a nearly Nernstian slope is at 0.4 sccm oxygen flow rate. Furthermore, the experimental results reveal that the sensors exhibit a high sensitivity of 58.5 ± 2.1 mV/decade in a wide range (10 −10 to 10 −1 M). The limit of detection (LOD) of ITO‐ISFET is 1.8 nM, which is lower than the minimum allowable Na + level in the human body and urine. Furthermore, the proposed ITO‐ISFET has the capability to detect Na + in real human patient urine without any dilution process.