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A Bloch surface wave (BSW) platform opens up new possibilities in the design of sensors and components for photonic circuits owing to its superior properties such as low propagation losses that enable long optical communication lengths and large surface sensing areas. However, most of the reported BSW platforms require a large number of alternating layers to realize the coupling of the surface wave mode. Additionally, although BSW modes have been investigated in the visible region and the near-infrared (NIR) region, only limited reports are available in the important mid-infrared (MIR) region. In this study, we demonstrated a BSW platform consisting of only two Ge/SiO2 pairs and realizing well-coupled BSW in a wide spectral range from the NIR to the MIR. Exploiting the large refractive index difference between Ge and SiO2, the proposed BSW multilayer structure is designed to possess only two pairs of layers with a smaller total thickness than any of the reported BSW platforms. The reported MIR BSW mode shows potential for determination of trace elements and molecule species attached on the surface of the proposed BSW structure. [ABSTRACT FROM AUTHOR]

In this study, we developed a rapid biomarker sensor with a high sensitivity and high selectivity by applying a bead-based immunosensing technique in a nanofluidic preconcentration device. Antibody-coated 300-nm beads and antigens were mixed and then pumped into a valve-integrated nanofluidic preconcentration device for collection and trapping. Because of size differences between the molecules and 300-nm beads, the antigen (molecule) in the mixed solution could be concentrated by up to 10,000-fold in 2 min, but the nanobeads could not be thus concentrated. After concentrated antigens and antibody-coated nanobeads were isolated, micro-particle tracking velocimetry was used to measure the Brownian diffusion of the nanobeads in real time to determine the antigen concentration. Through this preconcentration experiment, we demonstrated a rapid and high-sensitivity detection of prostate-specific antigen with a detection limit of 50 pg/ml in 20 min. [ABSTRACT FROM AUTHOR]

Laser devices produced via solution‐processed perovskite quantum dots (QDs) offer broad spectral tunability as well as ease of fabrication. Utilizing quasi‐bound states in the continuum (quasi‐BIC) modes, solution‐processed QD laser devices have been demonstrated with a nanostructure coated in a thin‐film gain media configuration. However, light leakage through thin‐film guiding from the cavity side edges becomes more pronounced when shrinking the cavity size, posing challenges for the miniaturization of quasi‐BIC‐based lasers. Here, the fabrication of well‐defined patterns of QDs via a solution process allows them to take advantage of the pattern edges to reduce losses through the cavity edges. A single‐mode BIC laser is reported by using CsPbBr3 QDs with a narrow linewidth of ≈0.1 nm. Importantly, a miniaturized quasi‐BIC laser is realized with a device size as small as 10 × 10 µm2, making it the smallest among existing solution‐processed BIC lasers. This work provides a strategy for developing ultra‐compact BIC lasers via solution‐processed gain media. [ABSTRACT FROM AUTHOR]

In this study, we developed a portable smartphone-based diffusometry for analyzing the C-reactive protein (CRP) concentration. An optimized fluorescence microscopic add-on system for a smartphone was used to image the 300 nm fluorescent beads. Sequential nanobead images were recorded for a period and the image data were used for fluorescence correlation spectrometric (FCS) analysis. Through the analysis, the nanobeads' diffusion coefficient was obtained. Further, the diffusion coefficients of the anti-CRP-coated nanobeads, which were suspended in the samples with various CRP concentrations, were estimated using smartphone-based diffusometry. After 10 min of reaction, the anti-CRP-coated nanobeads in a higher CRP concentration solution led to a lower diffusion coefficient. Based on the experiments, a linear sensing range of 1~8 µg/mL was found. [ABSTRACT FROM AUTHOR]