Gradient Waveguide Thickness Guided-Mode Resonance Biosensor

Abstract

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.

Polymer-Based Guided-Mode Resonance Sensors: From Optical Theories to Sensing Applications

“…Finally, a TiO 2 layer of gradient thickness (6.9 nm/mm) was deposited on a custommade fixture through sputtering. 73 2.1.2. GMR Structure Following the Configuration in Figure 3b.…”

“…First, 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 …”

Label-Free Physical Techniques and Methodologies for Proteins Detection in Microfluidic Biosensor Structures

“…In [ 328 ], an integrated into a microfluidic chip sensor based on gradient waveguide thickness guided-mode resonance (GWT-GMR) is proposed. The GWT-GMR sensor is a planar wedge-shaped Bragg grating waveguide.…”

Well-Designed Smartphone-Based Imaging Biosensor

“…The resolution of smartphoneembedded CMOS image sensor (CIS) cameras now exceeds 20 million pixels, and the pixel pitch has been reduced to about 1 μm. Recently, smartphone optical sensors using this high pixel density have been extensively used for bioimaging medical diagnosis in microfluidics [2][3][4][5][6][7][8][9][10][11]. For example, an optical fiber surface plasmon resonance (SPR) sensor system was reported by Bremer et al They used the flash and camera on the back of a smartphone to excite and interrogate the SPR sensor system [12].…”