S. Binu

Bio: S. Binu is an academic researcher from University of Kerala. The author has contributed to research in topics: Optical fiber & Fiber optic sensor. The author has an hindex of 5, co-authored 5 publications receiving 172 citations.

Fibre optic displacement sensor for the measurement of amplitude and frequency of vibration

Abstract: This paper reports the principle of operation, design aspects, experimentation and performance of an extrinsic fibre optic displacement sensor for the measurement of amplitude and frequency of vibration. The device consists of fibre optic transmitter, fibre optic probe, mini-shaker, power amplifier, dynamic signal analyser and photodiode detector. The fibre optic probe consists of two well-polished PMMA (polymethyl methacrylate) fibres cemented together along some distance over the length. The sensor is capable of measuring vibration amplitudes ranging from 0.008 to 0.74 mm within a frequency range of 75 to 275 Hz. The sensitivity of the device is found to be 0.893 V/mm over 0.6 to 2.1 mm range and - 0.226 V / mm over 2.9 to 5.9 mm range. The simplicity of the design, high degree of sensitivity, dynamic range and the low cost of the fabrication make it suitable for real field applications. With the emerging fly-by-light concept, the fibre optic probe solves many sensing problems in aircrafts. Moreover, accuracy and reliability are the excellent pay-offs of this fibre optic sensor.

PMMA (polymethyl methacrylate) fiber optic probe as a noncontact liquid level sensor

Abstract: This article reports the principle of operation, design aspects, experimentation, and performance of a noncontact fiber optic liquid level sensor. The sensor is based on the phenomenon of reflective concept. The device consists of fiber optic transmitter, fiber optic probe, floating reflector, photodiode detector, and digital multimeter. The fiber optic probe consists of two 60-cm-long PMMA (polymethyl methacrylate) fibers of diameter 1 mm, numerical aperture 0.5, core refractive index 1.492, and cladding refractive index 1.402. The fiber optic sensor is a promising alternative to other well-established methods for the measurement of liquid level due to its simplicity of design, high precision, long-term stability, linearity, high degree of sensitivity, dynamic range, noncontact sensing, and low cost of the fabrication make it suitable for applications in precise level control in analytical and process chemistry, biochemistry, bioanalytics, and on-line measurement or inspection of liquid level. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2114–2118, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25415

Fibre optic target reflectivity sensor

Abstract: This paper reports the principle of operation, the design aspects, experimentation and performance of a fibre optic target reflectivity sensor to examine the correlation between the detector output, variation in material type and the reflectivity properties of the materials tested. The device consists of a fibre optic transmitter, a fibre optic probe, target and a photodiode detector. The fibre optic probe consists of two well-polished PMMA (polymethyl methacrylate) fibres cemented together along some distance over the length. The principle of fibre optic lever displacement sensors is applied. Material effects are examined by preparing a variety of samples namely gold coated mirror, copper, brass, aluminium, steel and galvanized iron using the same polishing techniques. It is found that the response of the sensor changes with change of target surface. The results show that the fibre optic probe is capable of discriminating between materials. With the use of commercially available fibre, source and detector, the set-up proves to be simple, highly sensitive, low cost and versatile one, which can be adopted for on-line measurement or inspection of test components.

OTDR Based Fiber Optic Microbend Sensor for Distributed Sensing Applications in Structural Pressure Monitoring

Abstract: The ability to understand and monitor the distributed behaviour of extended, critical structures is recognized as a matter of increasing importance. Optical fibres offer unique advantages for spatially distributed measurement. An especially important feature is the one dimensional nature of the medium, since this offers unique advantages for spatially distributed measurement. This article describes the principle of operation, the design and performance of a novel single mode fiber based multipoint microbend pressure sensor architecture, which may be utilized in distributed measurement. The actual sensor element is a single mode fiber coupled to the measurand field through the usual microbend inducing structures. The sensor uses optical time domain reflectometry (OTDR) to detect pressure induced charges of backscatter power at many separate locations in the fiber as a function of length along a single fiber with no taps or branches. The sensitivity of this structure to microbend induced losses has been thoroughly characterized. This feature greatly increases the information from a single instrument and hence decreases the cost-benefit ratio.

Fiber-Optic Chemical Sensors and Biosensors (2008–2012)

Abstract: ■ CONTENTS Books, Reviews, and Articles of General Interest 488 Sensors for (Dissolved) Gases and Vapors 489 Hydrogen 489 Hydrocarbons 490 Oxygen 491 Ammonia 493 Carbon Dioxide 494 Nitrogen Oxides 494 Vapors of Organic Solvents 495 Sensors for Humidity, Water Fractions, Hydrogen Peroxide, and Hydrazine 495 Humidity 495 Water Fractions 496 Hydrogen Peroxide and Hydrazine 496 Sensors for pH Values, Ions, and Salinity 496 pH Values 496 Ions 497 Salinity and Ionic Strength 499 Sensors for Organic Species 499 Biosensors 500 Immunosensors 500 PNA-Based Biosensors (DNA, Aptamers) 501 Other Affinity Sensors 501 Enzymatic Biosensors 502 Whole Cell Sensors 502 Advanced Optical Sensing Schemes and Materials 503 Author Information 505 Corresponding Author 505 Notes 505 Biographies 505 Acknowledgments 505 References 505

Optical sensors based on plastic fibers.

Abstract: The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented.

Review of analytical figures of merit of sensors and biosensors in clinical applications

Abstract: Although the development of clinical sensors and biosensors has increased in recent years, improvements in sensitivity, selectivity, limits of detection, fast response and miniaturization are yet to be attained Health care appears to provide the best opportunity for sensor development Among the wide range of different sensors and biosensors, electrochemical biosensors are the most common in the clinical field, due to their high sensitivity and selectivity, portability, rapid response time and low cost This article provides an up-to-date overview of the analytical performance of sensors and biosensors in clinical applications by discussing recent improvements, particularly due to the impact of nanotechnology

Distributed Optical Fiber Sensing Based on Rayleigh Scattering

Abstract: Optical fiber sensors offer unprecedented features, the most unique of which is the ability of monitoring varia- tions of the observed physical field with spatial continuity along the fiber. These distributed optical fiber sensors are based on the scattering processes that originate from the interaction between light and matter. Among the three different scatter- ing processes that may take place in a fiber—namely Rayleigh, Raman and Brillouin scattering, this paper focuses on Rayleigh-based distributed optical fiber sensors. For a given optical frequency, Rayleigh-based sensors exploit the three main properties of light: intensity, phase and polarization. All these sensing mechanisms are reviewed, along with basic principles, main acquisition techniques and fields of application. Emphasis, however, will be put on polarization-based distributed optical fiber sensors. While they currently represent a niche, they offer promising unique features worth being considered in greater detail.

Vibration Detection Using Optical Fiber Sensors

Abstract: Condition monitoring of heavy electromechanical equipment is commonly accomplished in the industry using vibration analysis. Several techniques, mainly based on capacitive and piezoelectric accelerometers, have been applied for predictive maintenance. However, the negative influence of the electromagnetic interference (EMI) can be a real problem when electrical signals are used to detect and transmit physical parameters in noisy environments such as electric power generator plants with high levels of EMI. Optical fiber sensors are increasingly used because of the nonelectrical nature of signals. In this paper, the most frequently used vibration optical fiber sensors will be reviewed, classifying them by the sensing techniques and measurement principles. The main techniques, intensity modulation, fiber bragg gratings and Fabry-Perot Interferometry, will be reviewed here.