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Ahmad Ashrif A Bakar

Other affiliations: University of Queensland
Bio: Ahmad Ashrif A Bakar is an academic researcher from National University of Malaysia. The author has contributed to research in topics: Fiber Bragg grating & Surface plasmon resonance. The author has an hindex of 17, co-authored 129 publications receiving 1546 citations. Previous affiliations of Ahmad Ashrif A Bakar include University of Queensland.


Papers
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Journal ArticleDOI
17 Sep 2013-Sensors
TL;DR: This paper reviews two prominent areas; first: the pre-processing method for eliminating possible artifacts via appropriate preparation at the time of recording EMG signals, and second: a brief explanation of the different methods for processing and classifying EMG messages.
Abstract: Electromyography (EMG) signals are becoming increasingly important in many applications, including clinical/biomedical, prosthesis or rehabilitation devices, human machine interactions, and more. However, noisy EMG signals are the major hurdles to be overcome in order to achieve improved performance in the above applications. Detection, processing and classification analysis in electromyography (EMG) is very desirable because it allows a more standardized and precise evaluation of the neurophysiological, rehabitational and assistive technological findings. This paper reviews two prominent areas; first: the pre-processing method for eliminating possible artifacts via appropriate preparation at the time of recording EMG signals, and second: a brief explanation of the different methods for processing and classifying EMG signals. This study then compares the numerous methods of analyzing EMG signals, in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.

654 citations

Journal ArticleDOI
09 Apr 2014-Sensors
TL;DR: The current design, development and research of the optical fibre tactile techniques that are based on FBGs to enhance the performance of MIS procedures in general are described.
Abstract: The large interest in utilising fibre Bragg grating (FBG) strain sensors for minimally invasive surgery (MIS) applications to replace conventional electrical tactile sensors has grown in the past few years. FBG strain sensors offer the advantages of optical fibre sensors, such as high sensitivity, immunity to electromagnetic noise, electrical passivity and chemical inertness, but are not limited by phase discontinuity or intensity fluctuations. FBG sensors feature a wavelength-encoding sensing signal that enables distributed sensing that utilises fewer connections. In addition, their flexibility and lightness allow easy insertion into needles and catheters, thus enabling localised measurements inside tissues and blood. Two types of FBG tactile sensors have been emphasised in the literature: single-point and array FBG tactile sensors. This paper describes the current design, development and research of the optical fibre tactile techniques that are based on FBGs to enhance the performance of MIS procedures in general. Providing MIS or microsurgery surgeons with accurate and precise measurements and control of the contact forces during tissues manipulation will benefit both surgeons and patients.

97 citations

Journal ArticleDOI
TL;DR: In this article, the results from XRD analysis confirmed the successful incorporation of gold-chitosan-graphene oxide (Au/CS/GO) nanostructured thin films and Au/CS films.
Abstract: Optical sensors based on surface plasmon resonance (SPR) are utilized for detecting toxic heavy metals in solutions. To improve the sensitivity of SPR sensors, nanostructured thin films with active layers can be synthesized. In this study, the response to Pb (II) was measured and compared for SPR sensors incorporating gold–chitosan–graphene oxide (Au/CS/GO) nanostructured thin films and Au/CS films. The characterization of Au/CS/GO using FESEM analysis revealed a film composed of nanosheets with wrinkled, rough surfaces. The results from XRD analysis confirmed the successful incorporation of GO in the prepared films. Additionally, AFM analysis determined that the Au/CS/GO films had a root mean square (rms) roughness of 28.38 nm and were considerably rougher than the Au/CS films. Upon exposure to a 5 ppm Pb (II) ion solution, the Au/CS/GO films exhibited higher SPR sensitivity, as much as 1.11200 ppm−1, than Au/CS films, 0.77600 ppm−1. This enhancement of the SPR response was attributed to strong covalent bonding between CS and GO in these films. These results indicated that the Au/CS/GO films show potential for the detection of heavy metal pollution in environmental applications.

73 citations

Journal ArticleDOI
TL;DR: In this paper, the authors highlight the recent advances of carbon quantum dots (CQDs) application as the sensing materials in optical sensor technology and discuss the current challenges of the present and the perspective for the forthcoming future are critically assessed.
Abstract: An excellent photoluminescence properties of carbon quantum dots (CQDs) offers great potential in sensing applications. The remarkable optical properties are promptly accessible to be recorded as a potential sensing signal. This paper highlights the recent advances of CQDs application as the sensing materials in optical sensor technology. The modification of CQDs via physical and chemical approaches tremendously improves its physicochemical properties, producing an excellent sensing output. The interaction mechanism between CQDs and chemical analytes is analyzed through dipole-dipole interaction and charge transfer. Such interactions change their fluorescence properties, leading to the enhancement of fluorescence signals and improved the optical sensor performances. The incorporation of CQDs with numerous optical detection method further improve the optical sensor advancement. The application of CQDs as sensing materials in diverse optical sensing techniques is also discussed in this review. Finally, the current challenges of the present and the perspective for the forthcoming future are critically assessed in the concluding section.

62 citations

Journal ArticleDOI
28 Aug 2014-Sensors
TL;DR: This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors.
Abstract: Surface plasmon resonance (SPR) is a novel optical sensing technique with a unique ability to monitor molecular binding in real-time for biological and chemical sensor applications. Interferometry is an excellent tool for accurate measurement of SPR changes, the measurement and comparison is made for the sensitivity, dynamic range and resolution of the different analytes using interferometry techniques. SPR interferometry can also employ phase detection in addition to the amplitude of the reflected light wave, and the phase changes more rapidly compared with other approaches, i.e., intensity, angle and wavelength. Therefore, the SPR phase interferometer offers the advantages of spatial phase resolution and high sensitivity. This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes. The main application areas of SPR sensors are demonstrated, i.e., the Fabry-Perot interferometer, Michelson interferometer and Mach-Zehnder interferometer, with different configurations. The three interferometers are discussed in detail, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors.

62 citations


Cited by
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01 Jan 2016
TL;DR: The principles of fluorescence spectroscopy is universally compatible with any devices to read and is available in the digital library an online access to it is set as public so you can download it instantly.
Abstract: Thank you very much for downloading principles of fluorescence spectroscopy. As you may know, people have look hundreds times for their favorite novels like this principles of fluorescence spectroscopy, but end up in malicious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they cope with some harmful bugs inside their desktop computer. principles of fluorescence spectroscopy is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the principles of fluorescence spectroscopy is universally compatible with any devices to read.

2,960 citations

Book ChapterDOI
22 Apr 2012
TL;DR: In this article, the electromagnetic spectrum in Figure 1 illustrates the many different types of electromagnetic radiation, including gamma rays (γ-rays), X-rays, ultraviolet (UV) radiation, visible light, infrared (IR), microwaves, and radio waves.
Abstract: Spectroscopy is the study of matter interacting with electromagnetic radiation (e.g., light). The electromagnetic spectrum in Figure 1 illustrates the many different types of electromagnetic radiation, including gamma rays (γ-rays), X-rays, ultraviolet (UV) radiation, visible light, infrared (IR) radiation, microwaves, and radio waves. The frequency (ν) and wavelength (λ) ranges associated with each form of radiant energy are also indicated in Figure 1.

849 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a review of the current state of the art in the field of random distributed feedback feedback laser (RDFL) generation, and discuss existing and future applications of random fiber laser, including telecommunication and distributed long reach sensor systems.

410 citations

Book
01 Jan 2007
TL;DR: Computational Science and Engineering (CSE) is the multi-disciplinary field of computer-based modelling and simulation for studying scientific phenomena and engineering designs.
Abstract: Computational Science and Engineering (CSE) is the multi-disciplinary field of computer-based modelling and simulation for studying scientific phenomena and engineering designs. Modelling and simulation helps to validate theory, and makes it possible to analyse scenarios that would otherwise be too time-consuming, expensive, or dangerous to study by experiment. Data exploration helps to turn numbers into insight which is especially challenging in times of Big Data.

316 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a guided tour of laser feedback interferometry, from its origin and early development through its implementation to a slew of sensing applications, including displacement, distance, velocity, flow, refractive index, and laser linewidth measurement.
Abstract: This tutorial presents a guided tour of laser feedback interferometry, from its origin and early development through its implementation to a slew of sensing applications, including displacement, distance, velocity, flow, refractive index, and laser linewidth measurement Along the way, we provide a step-by-step derivation of the basic rate equations for a laser experiencing optical feedback starting from the standard Lang and Kobayashi model and detail their subsequent reduction in steady state to the excess-phase equation We construct a simple framework for interferometric sensing applications built around the laser under optical feedback and illustrate how this results in a series of straightforward models for many signals arising in laser feedback interferometry Finally, we indicate promising directions for future work that harnesses the self-mixing effect for sensing applications

302 citations