Label-Free EGFR Sensing by Using a Flexible IrOx Extended-Gate Field-Effect Transistor-Based Biosensor

In this research work, we present a flexible iridium oxide (IrO
_x
) extended-gate field-effect transistor (EGFET) biosensor for label-free detection of the epidermal growth factor receptor (EGFR) biomarker. IrO
_x
was employed as the sensing membrane material due to its excellent electrochemical properties, high conductivity, stability, biocompatibility, and ability to facilitate redox reactions. The IrO
_x
film was deposited on a flexible polyimide (PI) substrate through a sol–gel process and characterized using atomic force microscopy and X-ray photoelectron spectroscopy. As a pH sensor, the IrO
_x
EGFET exhibited a super-Nernstian sensitivity of 68.54 mV/pH with high linearity, a low hysteresis of ∼ 6 mV, and a drift rate of 0.50 mV/h at pH 7 over 12 h. For EGFR detection, the IrO
_x
surface was functionalized with 3-aminopropyltriethoxysilane and glutaraldehyde to immobilize anti-EGFR antibodies. The EGFR sensor demonstrated a wide linear detection range from 1 to 1000 ng/mL with a sensitivity of 11.78 mV/log(ng/mL) and a linearity of 99.8%, making it suitable for clinical EGFR monitoring in cancer patients. The flexible IrO
_x
EGFET shows promise for reliable label-free detection of EGFR.