Refractive Index Sensor Based on Gradient Waveguide Thickness Guided-Mode Resonance Filter

Hsiung, Chan-Te; Huang, Cheng-Sheng

doi:10.1109/lsens.2018.2883471

Cited by 9 publications

(9 citation statements)

References 25 publications

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“…We first used a simulation tool (DiffractMOD, RSoft Design Group) based on rigorous-coupled wave analysis to determine the optimal incident wavelength. Figure 2 a shows an example of the cross-section of one cycle of a GMR structure in the simulation model (the x - and y -directions are not to scale) with rounded corners based on a scanning electron microscopy examination of the fabricated devices [ 20 ].…”

Section: Resultsmentioning

confidence: 99%

“…Different designs and fabrication techniques have been adopted to achieve a gradient waveguide thickness such that a linear variable bandstop filter [ 20 , 26 , 27 ] is realized. The GWT-GMR sensor used in this study consists of three layers, as shown in Figure 1 b; the layers include a substrate of polyethylene terephthalate (PET), a replicated grating structure of an ultraviolet (UV) adhesive (Norland 68, NOA68), and a TiO 2 layer with gradient thickness.…”

Section: Methodsmentioning

confidence: 99%

“…The GWT-GMR sensor used in this study consists of three layers, as shown in Figure 1 b; the layers include a substrate of polyethylene terephthalate (PET), a replicated grating structure of an ultraviolet (UV) adhesive (Norland 68, NOA68), and a TiO 2 layer with gradient thickness. The detailed fabrication process can be found in a previous study [ 20 ]. In brief, the fabrication of the sensor mainly consists of three processes: electron-beam lithography (EBL), replica molding, and film deposition.…”

Section: Methodsmentioning

confidence: 99%

“…Then, the pattern was transferred to NOA68 on a PET substrate through replica molding. Finally, a TiO 2 layer of gradient thickness (6.9 nm/mm) was deposited on a custom-made fixture through sputtering [ 20 ].…”

Section: Methodsmentioning

confidence: 99%

“…Instead of using a graded duty cycle GMR sensor, previously, we used a gradient waveguide thickness GMR (GWT-GMR) sensor as a refractive index (RI) sensor [ 20 ]. GWT-GMR sensors can be fabricated inexpensively using replica molding on a plastic substrate.…”

Section: Introductionmentioning

confidence: 99%

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Gradient Waveguide Thickness Guided-Mode Resonance Biosensor

Yang

Chen

et al. 2021

Sensors

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Portable systems for detecting biomolecules have attracted considerable attention, owing to the demand for point-of-care testing applications. This has led to the development of lab-on-a-chip (LOC) devices. However, most LOCs are developed with a focus on automation and preprocessing of samples; fluorescence measurement, which requires additional off-chip detection instruments, remains the main detection method in conventional assays. By incorporating optical biosensors into LOCs, the biosensing system can be simplified and miniaturized. However, many optical sensors require an additional coupling device, such as a grating or prism, which complicates the optical path design of the system. In this study, we propose a new type of biosensor based on gradient waveguide thickness guided-mode resonance (GWT-GMR), which allows for the conversion of spectral information into spatial information such that the output signal can be recorded on a charge-coupled device for further analysis without any additional dispersive elements. A two-channel microfluidic chip with embedded GWT-GMRs was developed to detect two model assays in a buffer solution: albumin and creatinine. The results indicated that the limit of detection for albumin was 2.92 μg/mL for the concentration range of 0.8–500 μg/mL investigated in this study, and that for creatinine it was 12.05 μg/mL for the concentration range of 1–10,000 μg/mL. These results indicated that the proposed GWT-GMR sensor is suitable for use in clinical applications. Owing to its simple readout and optical path design, the GWT-GMR is considered ideal for integration with smartphones or as miniaturized displays in handheld devices, which could prove beneficial for future point-of-care applications.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gradient Waveguide Thickness Guided-Mode Resonance Biosensor

Yang

Chen

et al. 2021

Sensors

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Optical properties of guided-mode resonant gratings with linearly varying period

et al. 2022

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Thickness and Refractive Index Measurement System for Multilayered Samples

Liu

Weng

2021

IEEE Access

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In order to simultaneously obtain the thickness and refractive index for each layer of multilayered samples, this paper proposes a novel measurement system with a simple structure by using geometric optics. The key point of the overall structure is that the binary linear equation relation between the upper and lower planes of the layer can be known by the distances between laser spots reflected from the layer. Using two optical paths with different incident angles of laser beams, the CCD sensors capture the spot signal for image processing binarization and data sampling. After the obtained laser spots' spacing is substituted into the equations, the thicknesses and refractive indexes of the multilayered samples can be calculated and measured. The proposed measurement system is characterized numerically using simulations on the commercial software program Zemax and then experimentally tested using a laboratory-built prototype. The experiment results show that the refractive indexes and the thicknesses of three-layer samples were measured with high accuracy (with maximum measurement errors of 2.4% and 2% for a refractive index n and thickness d, respectively).INDEX TERMS Auto-focusing microscopy, multilayered samples, optical system, refractive index, Thickness.

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Refractive Index Sensor Based on Gradient Waveguide Thickness Guided-Mode Resonance Filter

Cited by 9 publications

References 25 publications

Gradient Waveguide Thickness Guided-Mode Resonance Biosensor

Gradient Waveguide Thickness Guided-Mode Resonance Biosensor

Optical properties of guided-mode resonant gratings with linearly varying period

Thickness and Refractive Index Measurement System for Multilayered Samples

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