scholarly journals Near cut-off wavelength operation of resonant waveguide grating biosensors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Balint Kovacs ◽  
Fabio Aldo Kraft ◽  
Zsolt Szabo ◽  
Yousef Nazirizadeh ◽  
Martina Gerken ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Optical Waveguides ◽  
Refractive Index Change ◽  
High Sensitivity ◽  
Cost Effective ◽  
Intensity Change ◽  
Wavelength Shift ◽  
Geometrical Parameters ◽  
Guided Mode ◽  
Wide Range

AbstractNumerical simulations and analytical calculations are performed to support the design of grating-coupled planar optical waveguides for biological sensing. Near cut-off and far from cut-off modes are investigated, and their characteristics and suitability for sensing are compared. The numerical simulations reveal the high sensitivity of the guided mode intensity near the cut-off wavelength for any refractive index change along the waveguide. Consequently, it is sufficient to monitor the intensity change of the near cut-off sensing mode, which leads to a simpler sensor design compared to those setups where the resonant wavelength shift of the guided mode is monitored with high precision. The operating wavelength and the sensitivity of the proposed device can be tuned by varying the geometrical parameters of the corrugated waveguide. These results may lead to the development of highly sensitive integrated sensors, which have a simple design and therefore are cost-effective for a wide range of applications. These numerical findings are supported with experimental results, where the cut-off sensing mode was identified.

scholarly journals 3D-Printable Carbon Nanotubes-Based Composite for Flexible Piezoresistive Sensors

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5482
Author(s):  
Chaima Fekiri ◽  
Ho Chan Kim ◽  
In Hwan Lee
Keyword(s):  
Carbon Nanotubes ◽  
Flexible Electronics ◽  
Applied Pressure ◽  
Structural Complexity ◽  
High Sensitivity ◽  
Cost Effective ◽  
Measurement Range ◽  
Resistance Change ◽  
Piezoresistive Pressure Sensor ◽  
Wide Range

The intersection between nanoscience and additive manufacturing technology has resulted in a new field of printable and flexible electronics. This interesting area of research tackles the challenges in the development of novel materials and fabrication techniques towards a wider range and improved design of flexible electronic devices. This work presents the fabrication of a cost-effective and facile flexible piezoresistive pressure sensor using a 3D-printable carbon nanotube-based nanocomposite. The carbon nanotubes used for the development of the material are multi-walled carbon nanotubes (MWCNT) dispersed in polydimethylsiloxane (PDMS) prepolymer. The sensor was fabricated using the direct ink writing (DIW) technique (also referred to as robocasting). The MWCNT-PDMS composite was directly printed onto the polydimethylsiloxane substrate. The sensor response was then examined based on the resistance change to the applied load. The sensor exhibited high sensitivity (6.3 Ω/kPa) over a wide range of applied pressure (up to 1132 kPa); the highest observed measurement range for MWCNT-PDMS composite in previous work was 40 kPa. The formulated MWCNT-PDMS composite was also printed into high-resolution 3-dimensional shapes which maintained their form even after heat treatment process. The possibility to use 3D printing in the fabrication of flexible sensors allows design freedom and flexibility, and structural complexity with wide applications in wearable or implantable electronics for sport, automotive and biomedical fields.

Lazy Wave Catenary Risers: Scaling Factors and Analytical Approximation of the Static Stress Range in the Touchdown Zone

2013 ◽  
Author(s):  
Lucile M. Quéau ◽  
Mehrdad Kimiaei ◽  
Mark F. Randolph
Keyword(s):  
Oil And Gas ◽  
Structural Response ◽  
High Sensitivity ◽  
Cost Effective ◽  
Analytical Approximation ◽  
Static Stress ◽  
Analytical Determination ◽  
Stress Range ◽  
Dynamic Amplification Factor ◽  
Wide Range

Offshore exploration and production of oil and gas continue to increase and move into ever deeper water. Steel catenary risers (SCRs) are one of the most cost effective type of risers in deep water. However, high sensitivity to vessel motions and hydrodynamic loading in the touchdown zone may limit the feasibility of SCR applications. In recent years, there has been a growing interest in the use of Lazy-wave catenary riser (LWR) due to their better fatigue performance in the touchdown zone through the damping effect of the buoyancy section. The design of LWR involves numerous parameters that lead to a wide range of configurations. Each of these configurations needs to be evaluated against several criteria with respect to geometry, strength and fatigue for instance. This paper presents how tools recently proposed to improve the design of standard SCRs can be extended to benefit LWR applications. The dimensionless groups governing the structural response of LWRs are established in the aim of easing sensitivity analysis to key input parameters for LWR design, assisting experiments and reducing the number of numerical simulations. Moreover, the DAF (dynamic amplification factor) approach for dynamic response which has previously been explored for SCRs could also be used to simplify design of LWRs. As DAF relies on the analytical determination of static response, this framework shows that analytical boundary layer solutions in conjunction with the use of a Winkler type soil model can efficiently and accurately predict the static stress range of LWRs observed in the TDZ.

On-site determination of bisphenol A in river water by a novel solid-state electrochemiluminescence quenching sensor

2017 ◽  
Vol 14 (2) ◽  
pp. 115 ◽  
Author(s):  
Xiaoying Wang ◽  
Yijie Wang ◽  
Meng Jiang ◽  
Yanqun Shan ◽  
Xiaobing Wang
Keyword(s):  
Solid State ◽  
Bisphenol A ◽  
River Water ◽  
Water Samples ◽  
High Sensitivity ◽  
Intensity Change ◽  
Electrospinning Technique ◽  
River Water Samples ◽  
Wide Range

Environmental contextBisphenol A is an endocrine disruptor, which may migrate and transfer to the environment where it presents a potential risk to the health of humans and animals. Herein, we demonstrate that electrospun nanofibers could be used to develop a highly efficient solid-state quenching sensor for on-site determination of bisphenol A in river water samples. The strategy has great potential for routine environmental analyses. AbstractA novel solid-state electrochemiluminescence (ECL) quenching sensor based on luminescent composite nanofibres for detection of bisphenol A (BPA) has been designed. Luminescent composite nanofibres of ruthenium(ii) tris(bipyridine) (Ru(bpy)32+)-doped core–shell Cu@Au alloy nanoparticles (Ru/Cu@Au) mixed with nylon 6 (PA6)–amino-functionalised multi-walled carbon nanotubes (MWCNTs), Ru/Cu@Au-MWCNTs-PA6, were successfully fabricated by a one-step electrospinning technique. The Ru/Cu@Au-MWCNTs-PA6 nanofibres, with a unique 3D nanostructure, large specific surface area and double Ru(bpy)32+-ECL signal amplification, exhibited excellent ECL photoelectric behaviours on a glassy carbon electrode. As a solid-state ECL sensor, the Ru/Cu@Au-MWCNTs-PA6 nanofibres can sensitively detect low concentrations of BPA by monitoring the BPA-dependent ECL intensity change. The detection limit for BPA is 10 pM, which is comparable or better than that in the reported assays. The sensor was successfully applied to on-site determination of BPA in river water samples obtained from eight different sampling sites with good recovery, ranging from 97.8 to 103.4%. The solid-state ECL sensor displayed wide-range linearity, high sensitivity and good stability, and has great potential in the field of environmental analyses.

scholarly journals Sensitivity Enhancement of Curvature Fiber Sensor Based on Polymer-Coated Capillary Hollow-Core Fiber

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3763 ◽  
Author(s):  
Luis A. Herrera-Piad ◽  
Iván Hernández-Romano ◽  
Daniel A. May-Arrioja ◽  
Vladimir P. Minkovich ◽  
Miguel Torres-Cisneros
Keyword(s):  
Fiber Optic ◽  
High Sensitivity ◽  
Single Mode ◽  
Cost Effective ◽  
Fiber Optic Sensor ◽  
Hollow Core ◽  
Sensing Applications ◽  
Optic Sensor ◽  
Wide Range ◽  
Core Fiber

In this paper, we propose and experimentally demonstrate a simple technique to enhance the curvature sensitivity of a bending fiber optic sensor based on anti-resonant reflecting optical waveguide (ARROW) guidance. The sensing structure is assembled by splicing a segment of capillary hollow-core fiber (CHCF) between two single-mode fibers (SMF), and the device is set on a steel sheet for measuring different curvatures. Without any surface treatment, the ARROW sensor exhibits a curvature sensitivity of 1.6 dB/m−1 in a curvature range from 0 to 2.14 m−1. By carefully coating half of the CHCF length with polydimethylsiloxane (PDMS), the curvature sensitivity of the ARROW sensor is enhanced to −5.62 dB/m−1, as well as an increment in the curvature range (from 0 to 2.68 m−1). Moreover, the covered device exhibits a low-temperature sensitivity (0.038 dB/°C), meaning that temperature fluctuations do not compromise the bending fiber optic sensor operation. The ARROW sensor fabricated with this technique has high sensitivity and a wide range for curvature measurements, with the advantage that the technique is cost-effective and easy to implement. All these features make this technique appealing for real sensing applications, such as structural health monitoring.

scholarly journals Label-Free Assays on the BIND System

2004 ◽  
Vol 9 (6) ◽  
pp. 481-490 ◽  
Author(s):  
Brian T. Cunningham ◽  
Peter Li ◽  
Stephen Schulz ◽  
Bo Lin ◽  
Cheryl Baird ◽  
...  
Keyword(s):  
Fluorescent Dyes ◽  
Dynamic Range ◽  
Low Cost ◽  
High Sensitivity ◽  
Receptor Expression ◽  
Label Free ◽  
Protein Protein Interaction ◽  
Small Molecule Screening ◽  
Guided Mode ◽  
Wide Range

Screening of biochemical interactions becomes simpler, less expensive, and more accurate when labels, such as fluorescent dyes, radioactive markers, and colorimetric reactions, are not required to quantify detected material. SRU Biosystems has developed a biosensor technology that is manufactured on continuous sheets of plastic film and incorporated into standard microplates and microarray slides to enable label-free assays to be performed with high throughput, high sensitivity, and low cost per assay. The biosensor incorporates a narrow band guided-mode resonance reflectance filter, in which the reflected color is modulated by the attachment/detachment of biochemical material to the surface. The technology offers 4 orders of linear dynamic range and uniformity within a plate, with a coefficient of variation of 2.5%. Using conventional biochemical immobilization surface chemistries, a wide range of assay applications are enabled. Small molecule screening, cell proliferation/cytotoxicity, enzyme activity screening, protein-protein interaction, and cell membrane receptor expression are among the applications demonstrated.

Instantaneous-Stiffness Plane Analysis of Underactuated Fingers

2015 ◽  
Author(s):  
Bruno Belzile ◽  
Lionel Birglen
Keyword(s):  
Numerical Simulations ◽  
Theoretical Framework ◽  
Geometrical Parameters ◽  
Stiffness Analysis ◽  
Force Magnitude ◽  
Plane Analysis ◽  
Wide Range ◽  
The Relationship ◽  
Shed Light ◽  
Underactuated Finger

The general stiffness of an underactuated finger as seen from the actuator is a function of its internal compliant elements, such as springs, but also depends on its geometry. In this paper, a complete stiffness analysis of a general underactuated finger is presented. The objective is to shed light on important aspects to consider while designing underactuated fingers and how to take advantage of the finger’s stiffness during grasping, for instance in order to estimate information such as contact location and force magnitude. This is done using the instantaneous-stiffness plane of the finger introduced in this paper. This plane shows the relationship between the finger’s geometry and its instantaneous stiffness and how simple changes in geometrical parameters can have significant effects on the finger’s stiffness. This novel tool can be used for a wide range of underactuated finger architectures as will be shown. First, a theoretical framework including numerical simulations is presented. This is then followed by an optimization example of a finger’s geometry and a discussion.

scholarly journals Highly sensitive multicore fiber accelerometer for low frequency vibration sensing

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Josu Amorebieta ◽  
Angel Ortega-Gomez ◽  
Gaizka Durana ◽  
Rubén Fernández ◽  
Enrique Antonio-Lopez ◽  
...  
Keyword(s):  
Low Frequency ◽  
High Sensitivity ◽  
Single Mode ◽  
Wavelength Shift ◽  
Light Power ◽  
Low Frequency Vibration ◽  
Highly Sensitive ◽  
Wide Range ◽  
Vibration Sensing ◽  
Multicore Fiber

Abstract We report on a compact, highly sensitive all-fiber accelerometer suitable for low frequency and low amplitude vibration sensing. The sensing elements in the device are two short segments of strongly coupled asymmetric multicore fiber (MCF) fusion spliced at 180° with respect to each other. Such segments of MCF are sandwiched between standard single mode fibers. The reflection spectrum of the device exhibits a narrow spectrum whose height and position in wavelength changes when it is subjected to vibrations. The interrogation of the accelerometer was carried out by a spectrometer and a photodetector to measure simultaneously wavelength shift and light power variations. The device was subjected to a wide range of vibration frequencies, from 1 mHz to 30 Hz, and accelerations from 0.76 mg to 29.64 mg, and performed linearly, with a sensitivity of 2.213 nW/mg. Therefore, we believe the accelerometer reported here may represent an alternative to existing electronic and optical accelerometers, especially for low frequency and amplitude vibrations, thanks to its compactness, simplicity, cost-effectiveness, implementation easiness and high sensitivity.

2D Color-Intensity Representation of Ultrasonic Thickness Gauge Measurements

2020 ◽  
pp. 1192-1198
Author(s):  
M.S. Mohammad ◽  
Tibebe Tesfaye ◽  
Kim Ki-Seong
Keyword(s):  
Cost Effective ◽  
The Other ◽  
Thickness Gauge ◽  
Color Intensity ◽  
Digital Readout ◽  
Flat Surfaces ◽  
Video Cameras ◽  
Wide Range ◽  
Cost Effective Alternative ◽  
Ultrasonic Thickness

Ultrasonic thickness gauges are easy to operate and reliable, and can be used to measure a wide range of thicknesses and inspect all engineering materials. Supplementing the simple ultrasonic thickness gauges that present results in either a digital readout or as an A-scan with systems that enable correlating the measured values to their positions on the inspected surface to produce a two-dimensional (2D) thickness representation can extend their benefits and provide a cost-effective alternative to expensive advanced C-scan machines. In previous work, the authors introduced a system for the positioning and mapping of the values measured by the ultrasonic thickness gauges and flaw detectors (Tesfaye et al. 2019). The system is an alternative to the systems that use mechanical scanners, encoders, and sophisticated UT machines. It used a camera to record the probe’s movement and a projected laser grid obtained by a laser pattern generator to locate the probe on the inspected surface. In this paper, a novel system is proposed to be applied to flat surfaces, in addition to overcoming the other limitations posed due to the use of the laser projection. The proposed system uses two video cameras, one to monitor the probe’s movement on the inspected surface and the other to capture the corresponding digital readout of the thickness gauge. The acquired images of the probe’s position and thickness gauge readout are processed to plot the measured data in a 2D color-coded map. The system is meant to be simpler and more effective than the previous development.

The Future of Plasma-Based Surface Engineering Techniques in Tribology (Keynote)

2005 ◽  
Author(s):  
Allan Matthews ◽  
Adrian Leyland
Keyword(s):  
Surface Engineering ◽  
Performance Enhancement ◽  
Bulk Material ◽  
Cost Savings ◽  
Cost Effective ◽  
Ceramic Coatings ◽  
Performance Improvements ◽  
Treatment Techniques ◽  
Wide Range ◽  
Macro Scale

Over the past twenty years or so, there have been major steps forward both in the understanding of tribological mechanisms and in the development of new coating and treatment techniques to better “engineer” surfaces to achieve reductions in wear and friction. Particularly in the coatings tribology field, improved techniques and theories which enable us to study and understand the mechanisms occurring at the “nano”, “micro” and “macro” scale have allowed considerable progress to be made in (for example) understanding contact mechanisms and the influence of “third bodies” [1–5]. Over the same period, we have seen the emergence of the discipline which we now call “Surface Engineering”, by which, ideally, a bulk material (the ‘substrate’) and a coating are combined in a way that provides a cost-effective performance enhancement of which neither would be capable without the presence of the other. It is probably fair to say that the emergence and recognition of Surface Engineering as a field in its own right has been driven largely by the availability of “plasma”-based coating and treatment processes, which can provide surface properties which were previously unachievable. In particular, plasma-assisted (PA) physical vapour deposition (PVD) techniques, allowing wear-resistant ceramic thin films such as titanium nitride (TiN) to be deposited on a wide range of industrial tooling, gave a step-change in industrial productivity and manufactured product quality, and caught the attention of engineers due to the remarkable cost savings and performance improvements obtained. Subsequently, so-called 2nd- and 3rd-generation ceramic coatings (with multilayered or nanocomposite structures) have recently been developed [6–9], to further extend tool performance — the objective typically being to increase coating hardness further, or extend hardness capabilities to higher temperatures.

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.

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