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Enhancing the repeatability and sensitivity of low-cost PCB, pH-sensitive field-effect transistors
Rhys Ashton1, Callum D Silver1, Toby W Bird1
1School of Physics, Engineering & Technology, University of York, York, YO10 5DD, UK.
Biosensors & Bioelectronics
|February 23, 2023
Summary
Researchers developed low-cost printed circuit board (PCB) pH sensors using electrodeposited iridium oxide (IrOx) films. Electrochemical polishing significantly improved IrOx film uniformity, resulting in beyond-Nernstian pH sensitivity and reliable performance for diverse applications.
Area of Science:
- Electrochemistry
- Materials Science
- Sensor Technology
Background:
- Discrete, extended gate pH-sensitive field-effect transistors (dEGFETs) on printed circuit boards (PCBs) offer a low-cost, manufacturable analytical technology.
- Electrodeposited iridium oxide (IrOx) films show potential for pH sensing due to high theoretical sensitivity, but often suffer from low sensitivity and poor reproducibility.
- A combined IrOx and dEGFET PCB system has not been previously realized.
Purpose of the Study:
- To demonstrate a novel dEGFET pH sensor on PCB utilizing electrodeposited IrOx films.
- To investigate the impact of IrOx film properties on pH sensitivity and repeatability.
- To establish a foundation for cost-effective, ubiquitous sensors for healthcare and environmental monitoring.
Main Methods:
- Fabrication of dEGFETs on PCBs with electrodeposited IrOx films.
- Electrochemical polishing of the extended gate electrode prior to IrOx deposition.
- Surface analysis techniques to characterize IrOx film composition and uniformity.
- Performance evaluation of dEGFETs for pH sensitivity and repeatability, including ampicillin detection.
Main Results:
- The developed dEGFETs exhibited reliable and repeatable beyond-Nernstian pH response.
- IrOx film uniformity, enhanced by electrochemical polishing, was critical for high pH sensitivity and repeatability.
- Polished electrodes yielded dEGFETs with a median sensitivity of 70.7 ± 5 mV/pH, significantly higher than non-polished controls (31.3 ± 14 mV/pH).
- The sensors successfully detected and quantified ampicillin via β-Lactamase activity.
Conclusions:
- Electrochemical polishing is key to achieving uniform IrOx films for high-performance dEGFET pH sensors.
- This work presents a viable, low-cost platform for advanced electrochemical sensing.
- The demonstrated sensor technology holds promise for addressing global challenges in healthcare and environmental monitoring.
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