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<p>This work presents a novel, cost-effective, and facile approach for fabricating an ultrasensitive Surface Enhanced Raman Scattering (SERS) sensor using copper nanowires (CuNWs) directly deposited on the surface of the pre-etched silicon substrate. Unlike conventional methods requiring complex surface modifications, our technique employs a simple 24h pre-etching process in a (1:1) hydrofluoric (HF) and ethanol solution, offering a practical alternative for large-scale or low-resource applications. The immersion plating of CuNWs was achieved by dipping the pre-etched Si surface in a (0.025) M of CuSO<sub>4</sub>.5H<sub>2</sub>O solution for (30) minutes, enabling spontaneous formation of a dense CuNWs network. Field Emission Scanning Electron Microscope (FE-SEM) confirmed the high density of distributed nanoscale pores (~ 3.2 × 10<sup>8</sup> pores/cm<sup>2</sup>) on the bare etched surface and a homogeneous coverage of vertically aligned CuNWs (~ 6.5 × 10<sup>9</sup> NWs/cm<sup>2</sup>) on the hybrid substrate. Compositional integrity of the CuNWs was validated by Energy Dispersive (EDS), while structural features were characterized via X-ray Diffraction (XRD), confirming their polycrystalline nature. Remarkably, the fabricated sensor exhibited a recorded enhancement factor (EF) of (2.11 × 10<sup>13</sup>) and an ultra-low detection limit (LOD) of (3.38 × 10<sup>–11</sup>) for nitrite anions over a broad concentration range (5 × 10<sup>–6</sup> to 5 × 10<sup>–12</sup>&#xa0;M). The outstanding SERS performance is attributed to the high aspect ratio, sharp edges, and large density of CuNWs on the surface which collectively generate abundant electromagnetic hotspots. This work demonstrates a scalable, low-cost route for producing efficient Cu-based SERS substrates and offers a promising platform for ultrasensitive chemical sensing, especially in resource-limited or field-deployable settings.</p>

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An improved sensing process of ultra low concentration of nitrite anions using pre-etched silicon decorated with copper nanowires

  • 期刊论文

  • 发表日期：

    2025年10月10日

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  • Intisar A. Naseef,
  • Alwan M. Alwan,
  • Mehdi Q. Zayer,
  • Layla A. Wali

摘要

This work presents a novel, cost-effective, and facile approach for fabricating an ultrasensitive Surface Enhanced Raman Scattering (SERS) sensor using copper nanowires (CuNWs) directly deposited on the surface of the pre-etched silicon substrate. Unlike conventional methods requiring complex surface modifications, our technique employs a simple 24h pre-etching process in a (1:1) hydrofluoric (HF) and ethanol solution, offering a practical alternative for large-scale or low-resource applications. The immersion plating of CuNWs was achieved by dipping the pre-etched Si surface in a (0.025) M of CuSO4.5H2O solution for (30) minutes, enabling spontaneous formation of a dense CuNWs network. Field Emission Scanning Electron Microscope (FE-SEM) confirmed the high density of distributed nanoscale pores (~ 3.2 × 108 pores/cm2) on the bare etched surface and a homogeneous coverage of vertically aligned CuNWs (~ 6.5 × 109 NWs/cm2) on the hybrid substrate. Compositional integrity of the CuNWs was validated by Energy Dispersive (EDS), while structural features were characterized via X-ray Diffraction (XRD), confirming their polycrystalline nature. Remarkably, the fabricated sensor exhibited a recorded enhancement factor (EF) of (2.11 × 1013) and an ultra-low detection limit (LOD) of (3.38 × 10–11) for nitrite anions over a broad concentration range (5 × 10–6 to 5 × 10–12 M). The outstanding SERS performance is attributed to the high aspect ratio, sharp edges, and large density of CuNWs on the surface which collectively generate abundant electromagnetic hotspots. This work demonstrates a scalable, low-cost route for producing efficient Cu-based SERS substrates and offers a promising platform for ultrasensitive chemical sensing, especially in resource-limited or field-deployable settings.