scholarly journals Graphene-Based Biosensors for Detection of Composite Vibrational Fingerprints in the Mid-Infrared Region

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1496
Author(s):  
Yijun Cai ◽  
Yanfen Hang ◽  
Yuanguo Zhou ◽  
Jinfeng Zhu ◽  
Jingwen Yang ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Graphene Nanoribbons ◽  
Infrared Region ◽  
Infrared Range ◽  
Label Free ◽  
Mid Infrared ◽  
Performance Limit ◽  
Wide Range ◽  
Vibrational Signals ◽  
Physical Insight

In this study, a label-free multi-resonant graphene-based biosensor with periodic graphene nanoribbons is proposed for detection of composite vibrational fingerprints in the mid-infrared range. The multiple vibrational signals of biomolecules are simultaneously enhanced and detected by different resonances in the transmission spectrum. Each of the transmission dips can be independently tuned by altering the gating voltage applied on the corresponding graphene nanoribbon. Geometric parameters are investigated and optimized to obtain excellent sensing performance. Limit of detection is also evaluated in an approximation way. Besides, the biosensor can operate in a wide range of incident angles. Electric field intensity distributions are depicted to reveal the physical insight. Moreover, another biosensor based on periodic graphene nanodisks is further proposed, whose performance is insensitive to the polarization of incidence. Our research may have a potential for designing graphene-based biosensor used in many promising bioanalytical and pharmaceutical applications.

scholarly journals Wide-Range Tunable Narrow Band-Stop Filter Based on Bilayer Graphene in the Mid-Infrared Region

2020 ◽  
Vol 12 (4) ◽  
pp. 1-9
Author(s):  
Yindi Wang ◽  
Hongxia Liu ◽  
Shulong Wang ◽  
Ming Cai
Keyword(s):  
Narrow Band ◽  
Infrared Region ◽  
Bilayer Graphene ◽  
Mid Infrared ◽  
Wide Range ◽  
Band Stop Filter

scholarly journals Ultrathin and Electrically Tunable Metamaterial with Nearly Perfect Absorption in Mid-Infrared

2019 ◽  
Vol 9 (16) ◽  
pp. 3358 ◽  
Author(s):  
Yuexin Zou ◽  
Jun Cao ◽  
Xue Gong ◽  
Ruijie Qian ◽  
Zhenghua An
Keyword(s):  
Resonant Mode ◽  
Infrared Region ◽  
Perfect Absorber ◽  
Geometrical Structures ◽  
Material Loss ◽  
Absorption Region ◽  
Perfect Absorption ◽  
Mid Infrared ◽  
Wide Range ◽  
Metal Insulator Metal

Metamaterials integrated with graphene exhibit tremendous freedom in tailoring their optical properties, particularly in the infrared region, and are desired for a wide range of applications, such as thermal imaging, cloaking, and biosensing. In this article, we numerically and experimentally demonstrate an ultrathin (total thickness < λ 0 / 15 ) and electrically tunable mid-infrared perfect absorber based on metal–insulator–metal (MIM) structured metamaterials. The Q-values of the absorber can be tuned through two rather independent parameters, with geometrical structures of metamaterials tuning radiation loss (Qr) of the system and the material loss (tanδ) to further change mainly the intrinsic loss (Qa). This concise mapping of the structural and material properties to resonant mode loss channels enables a two-stage optimization for real applications: geometrical design before fabrication and then electrical tuning as a post-fabrication and fine adjustment knob. As an example, our device demonstrates an electrical and on-site tuning of ~5 dB change in absorption near the perfect absorption region. Our work provides a general guideline for designing and realizing tunable infrared devices and may expand the applications of perfect absorbers for mid-infrared sensors, absorbers, and detectors in extreme spatial-limited circumstances.

scholarly journals Label-Free Amperometric Immunosensor Based on Versatile Carbon Nanofibers Network Coupled with Au Nanoparticles for Aflatoxin B1 Detection

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 5
Author(s):  
Yunhong Huang ◽  
Fei Zhu ◽  
Jinhua Guan ◽  
Wei Wei ◽  
Long Zou
Keyword(s):  
Carbon Nanofibers ◽  
Aflatoxin B1 ◽  
Au Nanoparticles ◽  
Limit Of Detection ◽  
Differential Pulse ◽  
Detection Methods ◽  
Soft Template ◽  
Label Free ◽  
Amperometric Immunosensor ◽  
Wide Range

Facile detection methods for mycotoxins with high sensitivity are of great significance to prevent potential harm to humans. Herein, a label-free amperometric immunosensor based on a 3-D interconnected carbon nanofibers (CNFs) network coupled with well-dispersed Au nanoparticles (AuNPs) is proposed for the quantitative determination of aflatoxin B1 (AFB1) in wheat samples. In comparison to common carbon nanotubes (CNTs), the CNFs network derived from bacterial cellulose biomass possesses a unique hierarchically porous structure for fast electrolyte diffusion and a larger electrochemical active area, which increases the peak current of differential pulse voltammetry curves for an immunosensor. Combined with AuNPs that are incorporated into CNFs by using linear polyethyleneimine (PEI) as a soft template, the developed Au@PEI@CNFs-based immunosensor showed a good linear response to AFB1 concentrations in a wide range from 0.05 to 25 ng mL−1. The limit of detection was 0.027 ng mL−1 (S/N = 3), more than three-fold lower than that of an Au@PEI@CNTs-based sensor. The reproducibility, storage stability and selectivity of the immunosensor were proved to be satisfactory. The developed immunosensor with appropriate sensitivity and reliable accuracy can be used for the analysis of wheat samples.

Tunable doublet lens based on dielectric metasurface using phase-change material

2020 ◽  
Vol 34 (28) ◽  
pp. 2050313
Author(s):  
Xingyi Li ◽  
Siqi Li ◽  
Guoxi Wang ◽  
Yufang Lei ◽  
Yunfan Hong ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Focal Length ◽  
Infrared Region ◽  
Optical Components ◽  
Mid Infrared ◽  
Infrared Wavelength ◽  
Active Devices ◽  
Coupling System ◽  
Wide Range

Metasurfaces have recently emerged to realize flat optical components with various functions and providing potential capabilities in manufacturing active devices. In this paper, a doublet lens for mid-infrared wavelength with tunable focal length has been proposed. The designed metalens consists of two dielectric metalenses with different focal lengths patterned on a phase-change materials Ge2Sb1Te4. The doublet lens is proved to have above 13% change in the focal length with the crystalline states shifting of the Ge2Sb1Te4. And the designed doublet lens can be operated in mid-infrared region from 2.41 [Formula: see text]m to 2.60 [Formula: see text]m. In addition, chromatic calibration can be achieved by adjusting the crystalline phases of the Ge2Sb1Te4. This compatible metalens promises potential for a wide range of applications in MIR region such as multi-spectrum imaging, optical coupling system and micrography.

scholarly journals Electro-absorption modulation in GeSn alloys for wide-spectrum mid-infrared applications

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Yun-Da Hsieh ◽  
Jun-Han Lin ◽  
Richard Soref ◽  
Greg Sun ◽  
Hung-Hsiang Cheng ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Wide Spectrum ◽  
Photonic Integrated Circuits ◽  
Oxide Semiconductor ◽  
Optical Modulation ◽  
Bandgap Energy ◽  
Infrared Range ◽  
Optical Modulators ◽  
Mid Infrared ◽  
Wide Range

AbstractSilicon-based electronic-photonic integrated circuits, which are compatible with state-of-the-art complementary metal-oxide-semiconductor processes, offer promising opportunities for on-chip mid-infrared photonic systems. However, the lack of efficient mid-infrared optical modulators on silicon hinders the utilization of such systems. Here, we demonstrate the Franz-Keldysh effect in GeSn alloys and achieve mid-infrared electro-absorption optical modulation using GeSn heterostructures on silicon. Our experimental and theoretical results verify that the direct bandgap energy of GeSn can be widely tuned by varying the Sn content, thereby realizing wavelength-tunable optical modulation in the mid-infrared range with a figure-of-merit greater than 1.5 and a broadband operating range greater than 140 nm. In contrast to conventional silicon-photonic modulators based on the plasma dispersion effect, our GeSn heterostructure demonstrates practical and effective Franz-Keldysh mid-infrared optical modulation on silicon, helping to unlock the potential of electronic-photonic integrated circuits in a wide range of applications.

Validated Stability Indicating HPTLC Method for the Estimation of Amoxapine in Different Stress Conditions

2019 ◽  
Vol 15 (3) ◽  
pp. 273-279
Author(s):  
Shweta G. Rangari ◽  
Nishikant A. Raut ◽  
Pradip W. Dhore
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Degradation Products ◽  
Analysis Data ◽  
Peak Height ◽  
Good Resolution ◽  
Stability Indicating ◽  
Limit Of Quantitation ◽  
Wide Range ◽  
Hptlc Method

Background:The unstable and/or toxic degradation products may form due to degradation of drug which results into loss of therapeutic activity and lead to life threatening condition. Hence, it is important to establish the stability characteristics of drug in various conditions such as in temperature, light, oxidising agent and susceptibility across a wide range of pH values.Introduction:The aim of the proposed study was to develop simple, sensitive and economic stability indicating high performance thin layer chromatography (HPTLC) method for the quantification of Amoxapine in the presence of degradation products.Methods:Amoxapine and its degraded products were separated on precoated silica gel 60F254 TLC plates by using mobile phase comprising of methanol: toluene: ammonium acetate (6:3:1, v/v/v). The densitometric evaluation was carried out at 320 nm in reflectance/absorbance mode. The degradation products obtained as per ICH guidelines under acidic, basic and oxidative conditions have different Rf values 0.12, 0.26 and 0.6 indicating good resolution from each other and pure drug with Rf: 0.47. Amoxapine was found to be stable under neutral, thermal and photo conditions.Results:The method was validated as per ICH Q2 (R1) guidelines in terms of accuracy, precision, ruggedness, robustness and linearity. A good linear relationship between concentration and response (peak area and peak height) over the range of 80 ng/spot to 720 ng/spot was observed from regression analysis data showing correlation coefficient 0.991 and 0.994 for area and height, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) for area were found to be 1.176 ng/mL and 3.565 ng/mL, whereas for height, 50.063 ng/mL and 151.707 ng/mL respectively.Conclusion:The statistical analysis confirmed the accuracy, precision and selectivity of the proposed method which can be effectively used for the analysis of amoxapine in the presence of degradation products.

scholarly journals Photonic Crystal Nanobeam Cavities for Nanoscale Optical Sensing: A Review

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 72 ◽  
Author(s):  
Da-Quan Yang ◽  
Bing Duan ◽  
Xiao Liu ◽  
Ai-Qiang Wang ◽  
Xiao-Gang Li ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Optical Waveguides ◽  
Optical Sensing ◽  
Early Stage ◽  
Disease Diagnosis ◽  
Label Free ◽  
Quality Factors ◽  
Integrated Sensor ◽  
Early Stage Disease ◽  
Wide Range

The ability to detect nanoscale objects is particular crucial for a wide range of applications, such as environmental protection, early-stage disease diagnosis and drug discovery. Photonic crystal nanobeam cavity (PCNC) sensors have attracted great attention due to high-quality factors and small-mode volumes (Q/V) and good on-chip integrability with optical waveguides/circuits. In this review, we focus on nanoscale optical sensing based on PCNC sensors, including ultrahigh figure of merit (FOM) sensing, single nanoparticle trapping, label-free molecule detection and an integrated sensor array for multiplexed sensing. We believe that the PCNC sensors featuring ultracompact footprint, high monolithic integration capability, fast response and ultrahigh sensitivity sensing ability, etc., will provide a promising platform for further developing lab-on-a-chip devices for biosensing and other functionalities.

scholarly journals Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 4
Author(s):  
Donggee Rho ◽  
Seunghyun Kim
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Sample Volume ◽  
Small Sample ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Cavity Structure

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

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