<p>This article presents a biosensor based on a two-dimensional rod-in-air photonic crystal slab with a hexagonal lattice, specifically designed for glucose detection in both urine and blood samples. The photonic band structure is studied using the plane-wave expansion (PWE) method, while sensing parameters are analyzed using the finite-difference time-domain (FDTD) method. To enhance device performance, the nanocavity width and radii of silicon rods above the w1 waveguide are optimized. The design provides a wide bandgap and strong optical confinement within the cavity, ensuring high sensitivity to refractive-index variations. The 2D and 3D configurations of the structure are investigated. The sensor demonstrates a noticeable frequency shift and significant variation in transmitted output power in response to minute refractive-index variations. Simulation results confirm high performance, achieving a maximum sensitivity of 850 nm/ RIU, a high quality factor of 1.8956<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13538_2025_1919_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">$\times $</EquationSource> <EquationSource Format="MATHML"><math> <mo>×</mo> </math></EquationSource> </InlineEquation>10<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13538_2025_1919_Article_IEq2.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="8" /> </InlineMediaObject> <EquationSource Format="TEX">$^\textrm{4}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mtext>4</mtext> </mmultiscripts> </math></EquationSource> </InlineEquation>, a low detection limit of 1.115<InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13538_2025_1919_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">$\times $</EquationSource> <EquationSource Format="MATHML"><math> <mo>×</mo> </math></EquationSource> </InlineEquation>10<InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13538_2025_1919_Article_IEq4.gif" Format="GIF" Height="11" Rendition="HTML" Resolution="72" Type="Linedraw" Width="18" /> </InlineMediaObject> <EquationSource Format="TEX">$^{-5}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mrow> <mo>-</mo> <mn>5</mn> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation> RIU, and a high figure of merit of <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13538_2025_1919_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">$\approx 8968$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>≈</mo> <mn>8968</mn> </mrow> </math></EquationSource> </InlineEquation> <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13538_2025_1919_Article_IEq6.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="47" /> </InlineMediaObject> <EquationSource Format="TEX">$\textrm{RIU}^{-1}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mtext>RIU</mtext> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </math></EquationSource> </InlineEquation>. Moreover, the device operates reliably over a wide temperature range (0–80 °C), and the effect of fabrication tolerances on performance is thoroughly analyzed. With its compact footprint of <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13538_2025_1919_Article_IEq7.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">$\approx 100$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>≈</mo> <mn>100</mn> </mrow> </math></EquationSource> </InlineEquation> <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13538_2025_1919_Article_IEq8.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="33" /> </InlineMediaObject> <EquationSource Format="TEX">$\mu m^2$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>μ</mi> <msup> <mi>m</mi> <mn>2</mn> </msup> </mrow> </math></EquationSource> </InlineEquation> and excellent sensing characteristics, the proposed sensor is a strong candidate for integration into on-chip photonic circuits.</p>

Design and Analysis of a Photonic Crystal Nanocavity Biosensor for Glucose Measurement

期刊论文
发表日期：

2025年10月18日

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Shivesh Kumar,
Mrinal Sen

摘要

This article presents a biosensor based on a two-dimensional rod-in-air photonic crystal slab with a hexagonal lattice, specifically designed for glucose detection in both urine and blood samples. The photonic band structure is studied using the plane-wave expansion (PWE) method, while sensing parameters are analyzed using the finite-difference time-domain (FDTD) method. To enhance device performance, the nanocavity width and radii of silicon rods above the w1 waveguide are optimized. The design provides a wide bandgap and strong optical confinement within the cavity, ensuring high sensitivity to refractive-index variations. The 2D and 3D configurations of the structure are investigated. The sensor demonstrates a noticeable frequency shift and significant variation in transmitted output power in response to minute refractive-index variations. Simulation results confirm high performance, achieving a maximum sensitivity of 850 nm/ RIU, a high quality factor of 1.8956 $\times $ $\times$ 10 $^\textrm{4}$ $^{4}$ , a low detection limit of 1.115 $\times $ $\times$ 10 $^{-5}$ $^{- 5}$ RIU, and a high figure of merit of $\approx 8968$ $\approx 8968$ $\textrm{RIU}^{-1}$ ${RIU}^{- 1}$ . Moreover, the device operates reliably over a wide temperature range (0–80 °C), and the effect of fabrication tolerances on performance is thoroughly analyzed. With its compact footprint of $\approx 100$ $\approx 100$ $\mu m^2$ $μ m^{2}$ and excellent sensing characteristics, the proposed sensor is a strong candidate for integration into on-chip photonic circuits.