“Biomarker detection and bulk refractive index sensing are important across multiple industries ranging from early medical diagnosis to chemical process quality control. The bulky size, high cost, and complex architecture of existing refractive index and biomarker sensing technologies limit their use to highly skilled environments like hospitals, large food processing plants, and research labs. Here, we demonstrate a compact and inexpensive refractive index sensor based on resonant dielectric photonic nanoantenna arrays or metasurfaces. These dielectric resonances support Mie dipole and asymmetric resonances that shift with changes in their external environment. A single-wavelength transmission measurement in a portable (<250 in.3), low-cost (<$4000) sensor shows sensitivity to 1.9 × 10–6 change in the fluid refractive index without the use of a spectrometer or other complex optics. Our sensor assembly allows for measurements using multiple metasurfaces with identical resonances or varying resonance types for enhanced diagnostics on the same chip. Furthermore, a 10 kDa culture filtrate peptide CFP-10, a marker for human tuberculosis, is detected with our sensor with 10 pM resolution. This system has the potential to enable facile, fast, and highly sensitive measurements with adequate limits of detection for personalized biomedical diagnoses.”
(a) Microfluidic diagram showing the fluid inlet (top circle), temperature stabilization channel, the main testing channel with the optically active area, and a fluid outlet (bottom circle). Fabrication processes are included in the Supporting Information. (b) Diagram showing three different metasurfaces and a reference channel with the overlaid reflectance mask. (c) Sensing chip showing three 500 micron square metasurfaces and a blank reference within a chromium reflectance mask. These are fabricated on a microscopic glass slide and bound within a PDMS microfluidic channel. The fluid inlet and outlet are shown above and below the chromium mask, respectively. Reproduced under Creative Commons Attribution 4.0 International License from I. O. Oguntoye., B. K. Simone., et al. Silicon Nanodisk Huygens Metasurfaces for Portable and Low-Cost Refractive Index and Biomarker Sensing., ACS Appl. Nano Mater. 2022, 5, 3, 3983–3991.
Figures and the abstract are reproduced from I. O. Oguntoye., B. K. Simone., et al. Silicon Nanodisk Huygens Metasurfaces for Portable and Low-Cost Refractive Index and Biomarker Sensing., ACS Appl. Nano Mater. 2022, 5, 3, 3983–3991., https://doi.org/10.1021/acsanm.1c04443 under Creative Commons Attribution 4.0 International License.
Read the original article: Silicon Nanodisk Huygens Metasurfaces for Portable and Low-Cost Refractive Index and Biomarker Sensing
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