Fabrication of Disposable Thin-Film Electrodes via Shadow Mask Technique for Sensitive Point-of-Care Detection of C-Reactive Protein, a Sepsis Biomarker

Point-of-care testing for sepsis refers to diagnostic technologies that rapidly and effectively detect sepsis using specific biomarkers. The development of thin-film electrodes (TFEs) for biosensing applications has been frequently reported in recent years. Notably, TFEs have been employed to develop biosensors for C-reactive protein (CRP), a key biomarker of sepsis. This study presents a straightforward and rapid method for fabricating TFEs on substrates using a shadow mask technique. The process employs commercially available polyvinyl chloride sticker film, serving as a disposable shadow mask, to create a three-electrode system (working electrode (WE), counter electrode (CE), and reference electrode (RE) on a poly-(methyl methacrylate) substrate. The sequential deposition of 20 nm of titanium (Ti) and 120 nm of gold (Au) formed the WE and CE, while the RE was fabricated by depositing titanium and silver (Ag). The fabricated TFEs were characterized by field emission scanning electron microscopy, atomic force microscopy, and energy-dispersive X-ray spectroscopy analyses, revealing notable differences in surface morphology and elemental composition. A specific aptamer for the CRP biomarker is immobilized on the surface of a TFE. The electrochemical biosensor demonstrated a linear range of 0.02-0.9 ng/mL and a limit of detection of 6.5 pg/mL, indicating high sensitivity for detecting the CRP biomarker.