Diffractive Optical Analysis for Refractive Index Sensing using Transparent Phase Gratings

Kumawat, Nityanand; Pal, Parama; Varma, Manoj M.

doi:10.1038/srep16687

Cited by 17 publications

(16 citation statements)

References 37 publications

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“…Tuning of optical properties of colorful ultrathin CS/PAA films can be achieved by controlling the rotational speed and the spin‐coating time, which is a direct consequence of the high refractive index contrast between the CS layer and PAA layer. (The refractive index of PAA and CS are 1.47 and 1.59, respectively). Photonic crystals’ period also influences the optical properties of the ultrathin CS/PAA films.…”

Section: Figurementioning

confidence: 99%

Color Tunable Ultrathin Films Capable of Healing Multiple Scratches

et al. 2016

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Healable films with structural color are highly desirable and have a variety of potential applications. However, combining structural color with self-healing properties to obtain new functional materials is a big challenge in current research. Herein, we present the first example of a color tunable, ultrathin film that can self-heal in response to external mechanical abrasion. It is designed based on intermolecular hydrogen bonding interaction; the synthetic strategy involves spin-coating of poly(acrylic acid) (PAA) and chitosan (CS). The successful preparation of ultrathin, healable, structural color films provides a new type of biomimetic material.One of the characteristic features of living systems is structural color, which can be detected in the outer shells of jewel beetles, wings of butterflies and on many other insects.[1] The structural color originates from spectrally selective reflection of visible light from a periodic modulation of refractive index rather than pigment, dye or luminescence. Inspired by natural biological structures, photonic crystals (PhCs), which are composite structures with a periodic arrangement of refractive index in one dimension, [2] two dimensions, [3] and three dimensions, [4] have been designed and fabricated. Recently, they have been gradually applied in a myriad of applications such as optical devices, [5] sensing materials, [6] display technologies, [7] solar cells [8] and so on. [9] One-dimensional photonic crystals (1DPhCs) have the simplest structures and are easy to handle because of their simple structures composed of alternately stacked thin-film layers with high and low refractive indices. [10] The dynamic coloration is generally achieved either by changing the thickness of the multilayers or the refractive index of individual layers through chemical reactions. [11] Although PhCs have substantial potential applications in the development of advanced functional materials, accidental scratches on optical films change the way light is transmitted and can even cause severe light scattering. Such scratches on optical films have to be healed to restore their original optical functions for further applications.[12] Ideally, if we can mimic the living biological systems more closely and endow the materials with self-healing properties, the designed materials will have extended service lives, which can facilitate their maintenance and increase their reliability with stable functionality. [13] However, combining structural color with self-healing property is an enormous challenge, and there is no report on this field to date.In general, polymers have great potential for self-healing due to the high mobility of the polymer chains under physiological conditions. Polyelectrolyte multilayers have a pronounced self-healing effect due to their mobility in response to environmental change. External stimuli such as pH, ionic strength, temperature, light, etc. affect ionization of the functional groups of the polyelectrolytes, which makes the polyelectrolyte multilayers st...

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Section: Figurementioning

confidence: 99%

Color Tunable Ultrathin Films Capable of Healing Multiple Scratches

et al. 2016

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“…Kumawat et al . proposed a refractive sensor based on the interferometric mixing of multiply reflected diffraction orders using transparent phase gratings 15 . Zhou et al .…”

Section: Introductionmentioning

confidence: 99%

Quasi-periodic concave microlens array for liquid refractive index sensing fabricated by femtosecond laser assisted with chemical etching

Zhang

Wang

Yin

et al. 2018

Sci Rep

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In this study, a high-efficiency single-pulsed femtosecond laser assisted with chemical wet etching method has been proposed to obtain large-area concave microlens array (MLA). The quasi-periodic MLA consisting of about two million microlenses with tunable diameter and sag height by adjusting laser scanning speed and etching time is uniformly manufactured on fused silica and sapphire within 30 minutes. Moreover, the fabricated MLA behaves excellent optical focusing and imaging performance, which could be used to sense the change of the liquid refractive index (RI). In addition, it is demonstrated that small period and high RI of MLA could acquire high sensitivity and broad dynamic measurement range, respectively. Furthermore, the theoretical diffraction efficiency is calculated by the finite domain time difference (FDTD) method, which is in good agreement with the experimental results.

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“…Graphene‐based electrical and mechanical biochemical sensors have already been demonstrated for efficient sensing of DNA, protein, gas, pH, and more . However, in terms of device level, compared to electrical and mechanical sensing devices, optical sensing devices (based on fibers, photonic crystal fibers, waveguides, prisms, opto‐fluidic, and optical interferometers) have many desirable advantages, such as ultra‐sensitivity, long‐term stability, immunity to electromagnetic interference, compact form, light weight, cost‐effectiveness, remote measuring capability, multiplexing or distributed sensing capability, multi‐functionality, and lab‐on‐fiber capability . The most important advantages in optical sensing are lowering the limit of detection (LOD) and increasing the specificity of label‐free sensing .…”

Section: Introductionmentioning

confidence: 99%

The Roadmap of Graphene‐Based Optical Biochemical Sensors

Shivananju

Liu

et al. 2016

Adv Funct Materials

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Graphene is a novel two‐dimensional material composed of a one‐atom‐thick planar sheet of sp2‐bonded carbon atoms perfectly arranged in a honeycomb lattice that has exceptional photonic and electronic properties. We believe that the true potential of graphene lies in optical sensors, especially for biochemical sensing in the diagnostics and health care sector. Graphene has extraordinary properties, such as a one‐atom thickness, extremely high surface‐to‐volume ratio, large surface area, ability to quench fluorescence, excellent biocompatibility, broadband light absorption, ultrafast response time, high mechanical strength, outstanding robustness, and flexibility. The working principle is based on whenever the biomolecules come into contact with graphene, the Fermi level shifts to either p‐type or n‐type, changing the opto‐electronic properties. The most important factors in graphene‐based optical sensing are lowering the limit of detection and increasing the specificity of label‐free biochemical sensing. This article comprehensively and critically reviews emerging graphene optical biochemical sensors. We first elaborate on their opto‐electronic properties, fabrication, numerical modeling and simulation, and then review various sensing applications, such as single‐cell detection, neural imaging and optogenetics, colorimetric multifunctional sensors, cancer diagnosis, protein and DNA sensing, and gas sensing. Finally, the roadmap of current and future trends in graphene‐based optical biochemical sensors is discussed.

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Diffractive Optical Analysis for Refractive Index Sensing using Transparent Phase Gratings

Cited by 17 publications

References 37 publications

Color Tunable Ultrathin Films Capable of Healing Multiple Scratches

Color Tunable Ultrathin Films Capable of Healing Multiple Scratches

Quasi-periodic concave microlens array for liquid refractive index sensing fabricated by femtosecond laser assisted with chemical etching

The Roadmap of Graphene‐Based Optical Biochemical Sensors

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