An ultra-thin and highly sensitive SARS-CoV-2 detection platform was demonstrated using a nano-porous anodic aluminum oxide (AAO) membrane. The membrane surface was functionalized to enable efficient trapping and identification of SARS-CoV-2 genomic targets through DNA-DNA and DNA-RNA hybridization. To immobilize the probe oligonucleotides on the AAO membrane, the pore surface was first coated with the linking reagents, 3-aminopropyltrimethoxysilane (APTMS) and glutaraldehyde (GA), by a compact vacuum infiltration module. After that, complementary target oligos with fluorescent modifier was pulled and infiltrated into the nano-fluidic channels formed by the AAO pores. The fluorescent signal applying the AAO membrane sensors was two orders stronger than a flat glass template. In addition, the dependence between the nano-pore size and the fluorescent intensity was evaluated. The optimized pore diameter d is 200 nm, which can accommodate the assembled oligonucleotide and aminosilane layers without blocking the AAO nano-fluidic channels. Our DNA functionalized membrane sensor is an accurate and high throughput platform supporting rapid virus tests, which is critical for population-wide diagnostic applications result in a page being rejected by search engines.

Raman spectroscopy using aluminum nitride (AlN) optical waveguides was demonstrated for organic compound analysis. The AlN waveguide device was prepared by reactive sputtering deposition and complementary-metal-oxide semiconductor (CMOS) processes. A fundamental waveguide mode was observed over a broad visible spectrum and the waveguide evanescent wave was used to excite the Raman signals of the test analytes. The performance of the waveguide sensor was characterized by measuring the Raman spectra of the benzene derivative mixtures consisting of benzene, anisole, and toluene. The compositions and concentrations were resolved by correlating the obtained Raman spectrum with the characteristic Raman peaks associated with C−C, C−H, and C−O functional groups. With the advantages of real-time detection and enhanced Raman signal intensity, the AlN waveguides provided a sensor platform for nondestructive and online chemical compound monitoring.

Chip-scale SARS-CoV-2 testing was demonstrated using silicon nitride (Si 3 N 4 ) nanoslot fluidic waveguides to detect a tagged oligonucleotide with a coronavirus DNA sequence. The slot waveguides were fabricated using complementary metal–oxide–semiconductor (CMOS) fabrication processes, including multiscale lithography and selective reactive ion etching (RIE), forming femtoliter fluidic channels. Finite difference method (FDM) simulation was used to calculate the optical field distribution of the waveguide mode when the waveguide sensor was excited by transverse electric (TE) and transverse magnetic (TM) polarized light. For the TE polarization, a strong optical field was created in the slot region and its field intensity was 14× stronger than the evanescent sensing field from the TM polarization. The nanoscale confinement of the optical sensing field significantly enhanced the light–analyte interaction and improved the optical sensitivity. The sensitivity enhancement was experimentally demonstrated by measuring the polarization-dependent fluorescence emission from the tagged oligonucleotide. The photonic chips consisting of femtoliter Si 3 N 4 waveguides provide a low-cost and high throughput platform for real-time virus identification, which is critical for point-of-care (PoC) diagnostic applications.

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