A novel, simple and low-temperature ultrasonic spray method was developed to fabricate the multiwalled carbon-nanotubes (MWCNTs) based extended-gate ?eld-effect transistors (EGFETs) as the pH sensor. With an acid-treated process, the chemically functionalized two-dimensional MWCNT network could provide plenty of functional groups which exhibit hydrophilic property and serve as hydrogen sensing sites. For the ?rst time, the EGFET using a MWCNT structure could achieve a wide sensing rage from pH = 1topH= 13. Furthermore, the pH sensitivity and linearity values of the CNT pH-EGFET devices were enhanced to 51.74 mV/pH and 0.9948 from pH = 1topH= 13 while the sprayed deposition reached 50 times. The sensing properties of hydrogen and hydroxyl ions show signi?cantly dependent on the sprayed deposition times, morphologies, crystalline and chemical bonding of acid-treated MWCNT. These results demonstrate that the MWCNT-EGFETs are very promising for the applications in the pH and biomedical sensors.
- Extended-Gate Field-Effect Transistor
- Multi-Walled Carbon Nanotube
- PH Sensor