Graphene oxide sensing layer enables low-cost SPR detection of mercury, lead, and zinc in water

Researchers at Universidad Técnica Particular de Loja, Escuela Superior Politécnica de Chimborazo (ESPOCH), Università della Calabria, and Universidad Ecotec have computationally designed and optimized a surface plasmon resonance (SPR) sensor for detecting trace mercury, lead, and zinc ions in water, using a graphene oxide sensing layer atop an aluminum/aluminum oxide plasmonic stack on a borosilicate glass prism.

Schematic representation of the borosilicate-supported (B-sil)/Al/Al2O3/nanomaterial SPR sensor. Image from: Electron

The team compared four carbon nanomaterials as candidate sensing layers: graphene oxide, reduced graphene oxide, pristine graphene, and semiconducting single-walled carbon nanotubes, and evaluated each for angular sensitivity, resonance linewidth, and detection limit using transfer-matrix modeling. While single-walled carbon nanotubes and reduced graphene oxide produced larger angular shifts, both introduced severe resonance broadening. Graphene oxide offered the most balanced response: a measurable resonance shift combined with a comparatively narrow, well-defined resonance dip.

Schematic representation of the borosilicate-supported (B-sil)/Al/Al2O3/nanomaterial SPR sensor. Image from: ElectronThe team compared four carbon nanomaterials as candidate sensing layers: graphene oxide, reduced graphene oxide, pristine graphene, and semiconducting single-walled carbon nanotubes, and evaluated each for angular sensitivity, resonance linewidth, and detection limit using transfer-matrix modeling. While single-walled carbon nanotubes and reduced graphene oxide produced larger angular shifts, both introduced severe resonance broadening. Graphene oxide offered the most balanced response: a measurable resonance shift combined with a comparatively narrow, well-defined resonance dip.

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