Kenneth T V Grattan

• BSc, PhD, DSc
• Head of Faculty at City, University of London

A refractive index (RI) and temperature dual-parameter sensor, based on a side-polished hole-assisted dual-core fiber (HADCF), has been proposed. In this sensor, SnO2 film has been deposited on the suspended core of HADCF by RF sputtering to produce loss mode resonance (LMR). The energy of the center core has been shown to be able to be coupled int...

Saccadic eye movements enable us to search for the target of interest in a crowded scene or, in the case of goal-directed saccades, to simply bring the image of the peripheral target to the very centre of the fovea. This mechanism extends the use of the superior image processing performance of the fovea over a large visual field. We know that visua...

This paper proposes a novel highly sensitive humidity sensor with temperature compensation, mainly consisting of a special modal interferometer bonded with thick polyimide (PI) solid films. The modal interferometer is constructed by splicing a special dual-mode fiber (DMF) with two sections of regular single mode fiber (SMF), forming an SDS (SMF-DM...

Previous research has identified the capabilities of artificial whisker sensor arrays as an innovative method of tracking and evaluating flow events and disturbances. In this work, a new approach is put forward, focusing on achieving enhanced sensitivity and improved performance of fibre-optic whisker sensors, based on the principle of fibre Bragg...

The optical Vernier effect scheme has proven to be a powerful tool for significantly enhancing the sensitivity of the interferometric sensors by combining two interferometers, provided that the Free Spectral Range (FSR) of each interferometer closely matches that of the other. However, the fabrication of a reference cell that precisely aligns with...

The dual-transducer support structure discussed has the advantages of a simple structure and low cost, as well as allowing for the use of both Traveling-Wave (TW) and Standing-Wave (SW) acoustic transportation, supporting its use in pharmaceutical and biochemical analysis, for example. By adjusting the distance between the vibrating plate and the r...

A cantilevered microfiber Bragg grating (CMFBG) sensor with high sensitivity and resonant frequency which can be designed as required, has been proposed and demonstrated using experimental, theoretical, and simulation methods. The CMFBG design can have a variable cross-section, and has been created to operate by receiving ultrasonic guided waves th...

Acoustic manipulation techniques have gained significant attention across various fields, particularly in medical diagnosis and biochemical research, due to their biocompatibility and non-contact operation. In this article, we review the broad range of biomedical applications of micro/nano-motors that use acoustic manipulation methods, with a speci...

This paper presents a compact fiber-optic sensor based on a fiber Bragg grating (FBG), partially bonded with thick polyimide (PI) films, for the simultaneous measurement of humidity and temperature. Half of the grating was attached to the PI film, while the rest of the grating remained bare. When the sensor was exposed to humidity and temperature c...

Real-time monitoring of the state of charge (SOC) of the batteries used in a wide variety of applications is becoming increasingly important, especially given the impetus by the current targets towards “net-zero”. In this research, an advanced approach was used involving fiber Bragg grating (FBG)-based sensors that were developed and implemented fo...

An optical fiber sensor based on a hole-assisted dual-core fiber (HADCF) has been proposed and experimentally demonstrated for dual-parameter measurements. The dual-mode interferometer created uses the LP01 mode and LP11 mode in the suspended core of a specialist optical fiber, combined with a directional coupler formed by using the suspended core...

Droplet actuation using surface acoustic wave (SAW) technology has recently been widely employed in “lab-on-a-chip” applications. In this article, SAWs generated by interdigital transducers (IDTs) were used to actuate microdroplets, where their velocity and direction could be adjusted by changing only the excitation phase shift, θ , of the voltag...

Swimming microrobots guided in the circulation system offer considerable promise in precision medicine but currently suffer from problems such as limited adhesion to blood vessels, intensive blood flow, and immune system clearance-all reducing the targeted interaction. A swimming microrobot design with clawed geometry, a red blood cell (RBC) membra...

Polarizers are an essential optical element for tailoring the polarization state of electromagnetic waves in a wide range of optical devices. Such polarizers, which exhibit a wide operating bandwidth and high performance, are attracting increasing attention, due to their extensive prospects for use in applications ranging from polarization imaging,...

A surface-mounted tilt sensor was designed and fabricated to measure the inclination angle of engineered structures or slopes in two directions. The device utilizes two strain-sensitive FBGs for tilt angle measurement bi-directionally and one strain-free FBG to provide temperature compensation. In this work, a tilt sensor prototype was fabricated u...

Recognizing that wavelength modulation spectroscopy (WMS) is particularly important in the development of high-sensitivity gas sensing systems, this paper presents a detailed analysis of the ${R_{1f}}/\Delta {I_1}$ WMS technique that has recently been successfully demonstrated for calibration-free measurements of the parameters that support detecti...

An innovative probe design, based on plastic optical fiber which has been designed around a side-polished fiber, bent into a ‘V’ shape, is reported. Such a probe offers an innovative approach to monitoring of the surrounding refractive index of the material under study. The underlying principle is that such a side-polished optical fiber configured...

This research introduces a novel label-free graphene oxide-coated dual-peak long-period grating sensor for measuring protein concentrations. It achieves high sensitivity (22 nm/(g/mL)) and a low limit of detection (0.9 µg/mL), demonstrating extremely high potential for fiber optic biosensor development.

We present a novel FBG-based pressure sensor for detection of pressure waves associated with pipe leaks. It includes the sensor design concept, sensor calibration in a pilot plant scale rig that mimics a water distribution network and the simulated pipeline leakage tests.

This paper reports the success of the joint research between Sydney Water and City, University of London to develop and implement innovative fibre-optic sensors to monitor the effect of water hammer on pump station infrastructure.

A comparative analysis of surface plasmon resonance and fluorescence detection methods employing molecularly imprinted polymers revealed their distinct capabilities in codeine detection, offering valuable insights for diverse applications requiring sensitive and specific drug analysis.

To achieve automated rock classification and improve classification accuracy, this work discusses an investigation of the combination of laser-induced breakdown spectroscopy (LIBS) and the use of one-dimensional convolutional neural networks (1DCNNs). As a result, in this paper, an improved Bayesian optimization (BO) algorithm has been proposed whe...

Due to the extremely complex working conditions, various health and safety hazards are present in underground coal mines, which cause economic losses and heavy casualties. Among these hazards, methane gas explosion and coal combustion are recognized as the two major hazards to miners. Traditional electronic sensors in mine safety monitoring systems...

Shape sensing is of importance for the manipulation of flexible needles. In this work, a 0.6 mm diameter stylet with five Fiber Bragg Gratings (FBGs) installed as triplets was designed and implemented and a novel model of local curvature was established. A gradient-based optimization method has been integrated into the complete algorithm for shape...

Using Cross-Correlation (CC) of the Time Difference Of Arrival (TDOA) to determine the flow speed of arriving flow structures using the bending of FBG sensors, demonstrating FBG sensors capability for source localization applications.

A new and easy-to-fabricate strain sensor has been developed, based on fiber Bragg grating (FBG) technology embedded into a thermoplastic polyurethane filament using a 3-dimensional (3D) printer. Taking advantage of the flexibility and elastic properties of the thermoplastic polyurethane material, the embedding of the FBG provides durable protectio...

A new design of optical Fiber Bragg Grating (FBG)-based sensor for the measurement of torsion (twist) has been developed, which, while offering a high level of accuracy, can be fabricated inexpensively using 3D printing technology. In this sensor design, an FBG is embedded inside the thermoplastic polyurethane (TPU) filament, which acts as the sens...

Battery storage has an important role to play in integrating large-scale renewable power generations and in transport decarbonization. Real-time monitoring of battery temperature profiles is indispensable for battery safety management. Due to the advantages of small size, resistance to corrosion, immunity to electromagnetic interference, and multip...

Accurate State of Charge (SOC) and State of Health (SOH) estimation is crucial to ensure safe and reliable operation of battery systems. Considering the intrinsic couplings between SOC and SOH, a joint estimation framework is preferred in real-life applications where batteries degrade over time. Yet, it faces a few challenges such as limited measur...

Microfluidics is used in many applications ranging from chemistry, medicine, biology and biomedical research, and the ability to measure pH values in-situ is an important parameter for creating and monitoring environments within a microfluidic chip for many such applications. We present a portable, optical fibre-based sensor for monitoring the pH b...

The aim of this study is to propose new methods to monitor operational clearances in oil-free screw compressors. The motivation has been to support research into leakage flows through generating data on clearance variations, and thus to develop systems that can be used for condition monitoring and control in industrial machines. By reviewing some m...

A magnetic field sensor based on a side-polished two-core fiber (SPTCF)-based Michelson interferometer (MI) has been developed and demonstrated. The magnetic field sensor is composed of a standard single mode fiber (SMF) and a section of tapered TCF. By side-polishing a segment of the TCF, the effective index of the exposed core can be made sensiti...

Combining the benefits of photothermal conversion in a doped optical fiber with the principle of Fiber Bragg Grating (FBG)-based temperature measurement, a new optical fiber method for the measurement of moisture content has been developed and its performance is reported. This novel all-fiber approach shows the important characteristics of fast res...

Over the past 20 years, there has been considerable progress in the development of research in the micro/nanorobotics area. Through major, rapid, investment in the field and the use of, for example, correlation techniques, many successes have been seen in both theoretical and experimental work, which have had applications in emerging areas such as...

Having good control over the speed and direction of non-contact transportation is critical in industry today, especially in areas such as the manufacturing of flat panel displays, silicon wafers of semi-silicon and a number of other electronic devices. In a dual transducer-type ultrasonic levitation-based transportation system, it is well known tha...

Research on compact, flexible optical sensors for water quality monitoring, specifically targeting heavy metal ion monitoring, has become extremely important due to the increasing number of water pollution incidents seen worldwide where such heavy metals are involved. Optical fiber-based sensors provide an excellent basis for creating new sensing s...

The design and performance of an innovative high-precision extensometer system, fabricated inexpensively using 3D printing technology, are discussed in this paper. In the development of the extensometer, an embedded Fiber Bragg Grating (FBG) strain sensor was 3D printed using a thermoplastic polyurethane (TPU) filament, which was used as the primar...

An innovative vibration sensor based on a Fabry-Perot interferometer (FPI) using fiber Bragg grating (FBG) reflectors was demonstrated in this work. The sensor was designed to be compact and easy to fabricate, independent of temperature, to overcome limitations seen in previous designs, providing an effective correction for temperature effects in F...

We demonstrate fiber few-mode interferometers based on a self-assembly surface corrugated grating using charged nano-particles. Initially, an abrupt taper (AT) was first created using a micro flame. The AT was then further outwardly stretched to make an elongated uniformed taper until the tapered diameter achieved a micron scale. The high order cor...

The electrical characteristics of quad-crescent-shaped silicon nanowire (NW) solar cells (SCs) are numerically analyzed and as a result their performance optimized. The structure discussed consists of four crescents, forming a cavity that permits multiple light scattering with high trapping between the NWs. Additionally, new modes strongly coupled...

Self-running piezoelectric robots have the advantages of being low cost, high load ratio and fast speed of operation, as well as showing few limitations in confined spaces or for underwater applications. Controlling the speed of motion of such robots by adjusting the Standing Wave Ratio (SWR) along the vibration plate of the robot is important. Com...

A data-driven regression model using Machine Learning (ML) coding has been developed to predict the state-of-the-charge of a battery based on a Fiber Bragg Grating-based sensor, achieving a supervised ML model accuracy of 99.95%.

We demonstrate fiber few-mode interferometers based on self-assembly surface corrugated grating using charged nano-particles for temperature sensors with a maximum resonant wavelength shift of 4.6 nm over 20°C - 60°C.

The detection of O2 using optical techniques has now become very important and significant progress has been made in this area over the past few years. The measurement of O2 concentration is a key parameter for diverse applications such as in life sciences, environmental monitoring, industry and biological research, and luminescence-based sensors a...

Inorganic–organic hybrid perovskite solar cells (PSCs) have recently seen considerable progress, and this has encouraged researchers to evolve and test numerous different and potentially improved device architectures. As a result, in this paper, a theoretical design for improving light absorption to obtain maximum photocurrent using NiO/GeSe core–s...

An optical ring resonator with third-order, or Kerr, nonlinearity will exhibit symmetry breaking between the two counterpropagating circulating powers when pumped with sufficient power in both the clockwise and counterclockwise directions. This is due to the effects of self- and cross-phase modulation on the resonance frequencies in the two directi...

Optical gyroscopes based on the Sagnac effect have been the mainstay of inertial navigation in aerospace and shipping for decades. These gyroscopes are typically realized either as ring-laser gyroscopes (RLGs) or fiber-optic gyroscopes (FOGs). With the recent rapid progress in the field of ultrahigh-quality optical whispering-gallery mode and ring...

A Fiber Bragg Grating (FBG)-based inclinometer has been developed for field use, designed to incorporate biaxial 3-dimensional (3D) printed tilt sensors (in which four FBGs were used). The inclinometer was characterized by examining its response to a wide range of tilts, over the range from 0° to 90°, towards the inclination axes. An excellent line...

An ultra-high sensitivity refractive index (RI) sensor, based on an in-line fiber Mach-Zehnder interferometer (MZI) and utilizing a special 40 μm fiber which has been specifically designed for the purpose, supporting only the LP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and LP <sub xmlns...

More than 400 works were submitted. About 20% of the works submitted were not accepted, underlining again the serious work of review of the Scientific Committee of IMEKO; this explains the generally high scientific level of the memories presented in the various sessions. Four Plenary Lectures were also held. The number of works presented Germany an...

CHAIRMAN’S WELCOME MESSAGE As General Chairman of the IMEKO XIX World Congress it is an honour and a privilege to welcome you to Lisbon, capital of Portugal, the western continental European country that in, the 15th century, gave new worlds to the World. The theme chosen for the Congress is “Fundamental and Applied Metrology”. By choosing this the...

In this work, a novel 3D-printed biaxial sensor system for tilt measurement, based primarily on the use of four Fiber Bragg Grating (FBG) devices, has been developed and its performance characterized. The tilt sensor system created is of a compact design and relatively small dimensions, making it ideally suited to a variety of industrial applicatio...

Optical, and especially fiber optic techniques for chemical sensing have become very attractive in recent decades for a wide variety of biomedical and industrial processes and considerable progress in research in this field has been seen, evidenced by the significant number of papers published over several decades, commercial products developed and...

The optical attractive force in tapered single-mode fibers (SMFs) is usually uniformly distributed around the tapered section and has been found to be important for trapping and manipulating targeted atoms and nanoparticles. In contrast, a peculiar phenomenon of the evanescent field splitting along the azimuth axis can be experimentally observed by...

An ultrasensitive hybrid fiber grating sensor has been designed and functionalized with a novel nanocomposite material for selective detection of lead ions in water. Sensor performance is enhanced using an artificial neural network-based calibration process.

We demonstrate a 1531.52 nm tunable diode laser -based sensor system that can be used to build a dense, wide-area sensor network for in situ multi-point detection of acetylene (C2H2) and ammonia (NH3) leaks in industrial safety applications. The detection limit of the sensor is 16 ppm for C2H2 and 228 ppm for NH3 using a 28 cm long single-pass gas...

Given the complex environment experienced in working mines, the vibration waves produced by processes such as rock fracture in deep formations usually show interference effects when monitored due to other signals, the so-called “clutter” in the signal, which are interfered with the clutter. At the same time, owing to the influence of system noise,...

Having a continuous mode of transportation, in the manufacturing and pharmaceutical industries, is desirable and this facilitated by the usage of dual transducer-type ultrasonic levitation-based transportation systems. It is well known that the structural and electrical parameters determine what can be transported continuously, but the relationship...

Correction for ‘Analysis of the effects of acoustic levitation to simulate the microgravity environment on the development of early zebrafish embryos’ by Li Li et al. , RSC Adv. , 2020, 10 , 44593–44600, DOI: 10.1039/D0RA07344J.

A 3D-printed tilt fiber sensor using a two-mode interferometer (TMFI) as the sensing mechanism has demonstrated. The TMFI was constructed by splicing single-mode fibers (SMF-28s) at both ends of a two-mode (TMF) to generate a comb-like interference spectrum sensitive to bending. A 3D-printed cantilever with a attached to one end was used to induce...

This paper reports on an extended (20-month) period of monitoring of humidity in situ at two locations in the sewer network operated by Sydney Water using a fibre optic network into which a series of Bragg Grating-based sensors had been installed. The locations (Eustace Street in Manly, Sydney and Old Toongabbie at Oakes Reserve, western Sydney, Au...

A fiber-optic displacement sensor with ~λ/400 spatial resolution, at an operating wavelength of ~1550 nm, using an off-axis fiber interferometer and achieving the best displacement resolution of 4-nm in the optical domain has been demonstrated.

An erbium-doped fiber ring laser proximity sensor with a high accuracy of ±16 nm, when the output power difference between the dual lasing wavelengths (~1560 nm) is smaller than 3 dB wavelength has been demonstrated.

Optical Fiber Sensor technology has shown major developments recently, especially in uses across a range of different industrial measurement situations. Several illustrative applications are considered, with the benefits and outcomes of their use reviewed.

Fibre Bragg Gratings are employed as input of a state-of-charge prediction algorithm for Lithium-ion batteries. Data gathered allowed the development of a dynamic time-warping algorithm for prediction of the state of charge of battery.

Overhead-line (OHL) installation errors and infrastructure wear significantly affect efficient current collection in electrified train operation. Optical-fibre based real-time monitoring of the pantograph-OHL interface on a 25 kV powered network is reported.

Compared with the use of other types of sensors, there are significant advantages in making measurements of low speed gas flows by using a fiber-optic ‘hot-wire’ sensor. Measurements of this type using intrinsically safe fiber optic technology play an important role in industry, especially in coal mine gas clearance, roadway ventilation and fire sa...

In recent years, newly emerging photovoltaic (PV) devices based on silicon nanowire solar cells (SiNW-SCs) have attracted considerable research attention. This is due to their efficient light-trapping capability and large carrier transportation and collection with compact size. However, there is a strong desire to find effective strategies to provi...

An operational, Fiber Bragg Grating (FBG)- based sensing system, specifically designed to monitor conditions in a harsh industrial environment is reported. The sensors used were placed inside tanks with high levels of methane (CH4), carbon dioxide (CO2) and hydrogen sulphide (H2S) gases and high relative humidity in the North Head sewage treatment...

A real-time state-of-charge (SOC) estimator based on the signals obtained from a Fibre Bragg Grating (FBG)-based sensor system is reported. The estimator has used a dynamic time-warping algorithm to determine the best fit, employing previously obtained experimental data. The strain data used were obtained from the optical signal monitored, providin...

In this paper, an all fiber optic sensor based on a Mach-Zehnder interferometer (MZI) has been proposed for the simultaneous measurement of underwater pressure and temperature, utilizing a dualmode fiber (DMF) which has been specially designed, and supporting only the LP01 and LP02 modes propagating in the fiber. In this design, an in-line MZI sens...

Based on the coupled Ginzburg-Landau equations and Jones matrices of the waveplates considered, a numerical model of an all-normal-dispersion fiber laser mode-locked by nonlinear polarization rotation has been proposed. The operating characteristics of the fiber laser discussed were studied numerically. It has been found that the proposed all-norma...

A novel sensing system based on single mode optical fiber in reflective configuration has been developed to measure the critical meniscus height (CMH) of low volumes of liquids, which is then used to calculate the contact angle. The sensing system has been designed especially for very low volumes of liquids (e.g. bio-liquids) and the work has demon...

The thermally coupled green band emission from excited Er³⁺ ions has been used in the past to create optical thermometers, by doping the material in various types of media, particularly glasses. Glasses are known to be excellent hosts for Er³⁺ ions: however, high temperatures (>900 K) are usually required for doping these ions into glasses and a no...

Mildew is an important issue in grain storage, due to the very expensive losses that can arise due to grain spoilage by mildew. Monitoring the conditions which allow mildew to develop is important and current monitoring technology cannot readily, or safely, be used for internal humidity monitoring of the very large quantities of grain kept in stora...

This work presents the design and optimization of a cascade nano-laser using CH3NH3PbI3 perovskite. Due to increasing threshold gain with decreasing device size and high Auger losses, the use of perovskite as the active medium in the cascade nano-laser was proposed, as the material possesses a high emission rate in the visible wavelength region, wi...

The microseismic monitoring signals which need to be determined in mines include those caused by both rock bursts and by blasting. The blasting signals must be separated from the microseismic signals in order to extract the information needed for the correct location of the source and for determining the blast mechanism. The use of a convolutional...

The design, synthesis and spectroscopic properties of novel polymerizable coumarin-based pH indicators are reported. They show a fluorescence response to pH in the highly alkaline pH region with calculated pKa values in the range of 12.2–12.5. Covalent immobilization of the indicators to polymer supports provides novel pH-sensitive materials that p...

We demonstrate a novel optical microresonator gyroscope whose responsivity to rotation is enhanced by a factor of around $10^4$ by operating close to the critical point of a spontaneous symmetry breaking transition between counterpropagating light. We present a proof-of-principle rotation measurement using a resonator with a diameter of 3 mm. In ad...

We demonstrate a real-time microanalysis approach to the evaporation rate of a (sub)picoliter liquid drop, measured over a 7.85-0.38 picoliter volume, using an off-axis fiber interferometer and achieving the best displacement resolution of 24 nm.

By tapering a weakly-coupled MCF into a strongly-coupled MCF, supermode interference effects can be generated with the best extinction ratio, 47.4dB and tuning efficiency, 392nm/RIU. Up-conversion nanoparticles are attracted and aligned by hexagonal evanescent fields.