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Exploring the ITO/PET Extended-Gate Field-Effect Transistor (EGFET) for pH Sensing
1Department of Electrical and Computer Engineering, California State University, Fresno, CA 93740, USA.
Sensors (Basel, Switzerland)
|October 28, 2023
Summary
This study developed an extended-gate field-effect transistor (EGFET) using Indium Tin Oxide/Polyethylene Terephthalate films as a pH sensor. The sensor demonstrated a consistent decrease in current with increasing pH, showing high sensitivity in sulfuric acid.
Area of Science:
- Materials Science
- Chemical Engineering
- Electronics Engineering
Background:
- Extended-gate field-effect transistors (EGFETs) offer potential for chemical sensing applications.
- Indium Tin Oxide (ITO) on Polyethylene Terephthalate (PET) provides a flexible and conductive platform for sensor development.
Purpose of the Study:
- To investigate the performance of an EGFET utilizing ITO/PET sensitive films as a pH sensor.
- To establish a correlation between electrical characteristics and pH variations in different chemical solutions.
Main Methods:
- Fabrication of an EGFET using CD4007 FETs and ITO/PET sensitive films.
- Testing the device's response to various acidic and basic solutions (hydrogen peroxide, acetic acid, sulfuric acid, ammonium hydroxide) at different concentrations.
- Measurement of current-voltage (I-V) characteristics using a Tektronix 4200A sourcemeter.
- Correlation analysis between drain current (ID), solution concentration, and measured pH values.
Main Results:
- The drain current (ID) exhibited a strong dependence on solution concentration.
- A consistent decrease in drain current was observed as the pH value increased across different solutions.
- The sensor achieved a high voltage sensitivity of 0.23 V per pH unit when tested with sulfuric acid.
Conclusions:
- The developed ITO/PET based EGFET functions effectively as a pH sensor.
- The sensor shows a predictable inverse relationship between drain current and pH.
- The device demonstrates promising sensitivity and potential for practical pH monitoring applications.
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