Surface refractive index sensor based on titanium dioxide composite thin film for detection of cadmium ions

Omar, Nur Alia Sheh; Ramli, Irmawati; Fen, Yap Wing; Muhamad, Ernee Noryana; Eddin, Faten Bashar Kamal; Anas, Nur Ain Asyiqin; Ramdzan, Nur Syahira Md; Fauzi, Nurul Illya Muhamad; Mahdi, Mohd Adzir

doi:10.1016/j.measurement.2021.110287

Cited by 15 publications

(2 citation statements)

References 34 publications

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“…To determine the refractive index and the thickness of the Au/CQD thin film, the SPR experimental curves were fitted using a developed fitting program based on Fresnel equations [ 77 , 78 , 79 , 80 , 81 , 82 , 83 ] ( Figure 4 b–h). The obtained refractive index of the gold film was found to be in good agreement with previous studies [ 84 , 85 ], which yielded the n - and k -values of 0.276 and 3.897, respectively, with a thickness of 57.1 nm. The n - and k -values of the DA solution were the same as deionized water for concentrations less than 10 pM; after that, the k -value increased to 0.003.…”

Section: Resultssupporting

confidence: 90%

Direct and Sensitive Detection of Dopamine Using Carbon Quantum Dots Based Refractive Index Surface Plasmon Resonance Sensor

et al. 2022

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Abnormality of dopamine (DA), a vital neurotransmitter in the brain’s neuronal pathways, causes several neurological diseases. Rapid and sensitive sensors for DA detection are required for early diagnosis of such disorders. Herein, a carbon quantum dot (CQD)-based refractive index surface plasmon resonance (SPR) sensor was designed. The sensor performance was evaluated for various concentrations of DA. Increasing DA levels yielded blue-shifted SPR dips. The experimental findings revealed an excellent sensitivity response of 0.138°/pM in a linear range from 0.001 to 100 pM and a high binding affinity of 6.234 TM−1. The effects of varied concentrations of DA on the optical characteristics of CQD thin film were further proved theoretically. Increased DA levels decreased the thickness and real part of the refractive index of CQD film, according to fitting results. Furthermore, the observed reduction in surface roughness using AFM demonstrated that DA was bound to the sensor layer. This, in turn, explained the blue shift in SPR reflectance curves. This optical sensor offers great potential as a trustworthy solution for direct measurement due to its simple construction, high sensitivity, and other sensing features.

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Section: Resultssupporting

confidence: 90%

Direct and Sensitive Detection of Dopamine Using Carbon Quantum Dots Based Refractive Index Surface Plasmon Resonance Sensor

et al. 2022

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“…It consisted of a He-Ne laser which was used as an excitation beam with a fixed wavelength at 632.8 nm, a beam chopper, a linear polarizer, a tiny pinhole, a triangular prism with a refractive index of 1.77861, an optical programmable gyratory platform driven by a motion controller (Newport model MM 3000) with a resolution of 0.001°, a photodetector, and a lock-in amplifier, as shown in Figure 2 . The uncoated surface of the SPR chip was linked to the prism using the index matching liquid, and the flow cell that contains the sample solution made touch with the sensor chip’s surface [ 55 , 56 , 57 , 58 ]. Afterward, SPR tests were performed in a dark environment using CS/Au sensor films in contact with DW initially, then with different concentrations of DA.…”

Section: Methodsmentioning

confidence: 99%

Plasmonic Refractive Index Sensor Enhanced with Chitosan/Au Bilayer Thin Film for Dopamine Detection

et al. 2022

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Surface plasmonic sensors have received considerable attention, found extensive applications, and outperformed conventional optical sensors. In this work, biopolymer chitosan (CS) was used to prepare the bilayer structure (CS/Au) of a plasmonic refractive index sensor for dopamine (DA) detection. The sensing characteristics of the developed plasmonic sensor were evaluated. Increasing DA concentrations significantly shifted the SPR dips. The sensor exhibited stability and a refractive index sensitivity of 8.850°/RIU in the linear range 0.1 nM to 1 µM with a detection limit of 0.007 nM and affinity constant of 1.383 × 108 M−1. The refractive index and thickness of the CS/Au structure were measured simultaneously by fitting the obtained experimental findings to theoretical data based on Fresnel equations. The fitting yielded the refractive index values n (1.5350 ± 0.0001) and k (0.0150 ± 0.0001) for the CS layer contacting 0.1 nM of DA, and the thickness, d was (15.00 ± 0.01) nm. Then, both n and d values increased by increasing DA concentrations. In addition, the changes in the FTIR spectrum and the variations in sensor surface roughness and structure obtained by AFM analysis confirmed DA adsorption on the sensing layer. Based on these observations, CS/Au bilayer has enhanced the performance of this plasmonic sensor, which showed promising importance as a simple, low-cost, and reliable platform for DA sensing.

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Advanced nanostructures plasmonics noninvasive sensors for type 1 diabetes

Subramaniam¹,

Trabelsi

Azarkaman

et al. 2022

Opt Quant Electron

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Surface refractive index sensor based on titanium dioxide composite thin film for detection of cadmium ions

Cited by 15 publications

References 34 publications

Direct and Sensitive Detection of Dopamine Using Carbon Quantum Dots Based Refractive Index Surface Plasmon Resonance Sensor

Direct and Sensitive Detection of Dopamine Using Carbon Quantum Dots Based Refractive Index Surface Plasmon Resonance Sensor

Plasmonic Refractive Index Sensor Enhanced with Chitosan/Au Bilayer Thin Film for Dopamine Detection

Advanced nanostructures plasmonics noninvasive sensors for type 1 diabetes

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