On-chip infrared metasurface glucose sensor based on asymmetric hook-shaped nanoantenna arrays.

Mid-infrared plasmonic metasurfaces are promising for label-free biomolecular fingerprinting. This study presents an asymmetric hook-shaped nanoantenna array for surface-enhanced infrared absorption (SEIRA) spectroscopy. Through systematic 3D finite-difference time-domain (FDTD) simulations, the influence of antenna thickness, shape, lattice periodicity and polarization angle on optical response and near-field enhancement were investigated. The optimized geometry exhibits an absorption peak at ∼9.67 μm, coinciding with the characteristic vibrational modes of glucose. When configured as a glucose sensor incorporating background correction and multi-peak fitting algorithms, the platform delivers a 22.24-fold boost in extinction intensity and an enhancement factor (EF) exceeding 104 relative to a conventional CaF2 substrate. Preliminary tests in fetal bovine serum (FBS) indicate the robustness of the extracted glucose vibrational features in a complex matrix. All data points fall within Zone A of the Clarke Error Grid (CEG), and Bland-Altman (BA) analysis shows good agreement, with a root mean square error (RMSE) of 4.88 mg/dL. No discernible interference from the FBS background was observed.