[16a-P07-1~24] 3.11 Nanoscale optical science and near-field optics

[16a-P07-2] Photocurrent Detection Type Silicon Metasurface Biosensor (1)

〇(M1)Naoki Kaneda¹, Keisuke Moriasa¹, Hiroshi Sugimoto¹, Minoru Fujii¹ (1.Kobe Univ.)

Keywords:

Nanophotonics,Metasurface,Biosensor

A two-dimensional array of silicon nanodisks (Si NDs) supports toroidal dipole resonance, which strongly confines electromagnetic waves and enhances light absorption at the resonance wavelength. When formed on a silicon thin film, the Si ND array significantly enhances photocurrent, especially below silicon's bandgap, where narrowband enhancement peaks are observed. We are developing a photocurrent-based biosensor that detects analyte adsorption on the ND surface by refractive index changes, which shift the absorption peak wavelength. This shift is measured as a photocurrent change. The device comprises a Si ND array integrated into a microfluidic channel with electrodes for photocurrent detection. Monochromatic light at the resonance wavelength enables detection without complex optics. Simulations validated the principle, and prototypes fabricated with nanosphere lithography showed a sharp absorption peak. Measurements demonstrated strong field confinement and effective analyte detection.