Copper-graphene nanohole array based dual-mode sensor for wide RI range for the detection of analytes

Abstract Nanohole array-based surface plasmon resonance (SPR) sensors have emerged as highly sensitive devices capable of detecting subtle changes in refractive index (RI) across a wide range. In this work, a novel copper-graphene nanohole array sensor with a silicon dioxide (SiO 2 ) substrate is presented, designed to enhance sensitivity and maintain stability at a low cost. The integration of a thin graphene layer serves to mitigate copper’s adverse effects, such as oxidation, while retaining the high conductivity needed for effective SPR. Numerical simulations demonstrate a wide-ranging resonance peak between 650 nm and 850 nm, achieving remarkable sensitivity across a wide range of RI 1.2 to 2. Notably, dual SPR peaks are observed starting from an RI of 1.4, enhancing the sensor’s detection range. The highest sensitivity achieved for RIs up to 1.4 is 516.67 nm RIU −1 with a full width at half maximum (FWHM) of 67.53 nm, while for RIs between 1.4 and 1.8, Mode 1 sensitivity peaks at 434.23 nm RIU −1 (FWHM of 72.58 nm) and Mode 2 at 623.20 nm RIU −1 (FWHM of 73.75 nm). This wide RI range and dual-mode functionality make the sensor suitable for diverse applications. The sensor’s performance is validated in detecting key blood molecules ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mi mathvariant="italic">Na</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mi>K</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:math> , glucose) by measuring their specific RI sensitivities. This copper-graphene nanohole array sensor offers a promising solution for cost-effective, high-sensitivity biosensing across biomedical and chemical industries, specifically for point-of-care diagnostics and chemical analysis.