Imperial College London

ProfessorRichardSyms

Faculty of EngineeringDepartment of Electrical and Electronic Engineering

Professor
 
 
 
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Contact

 

+44 (0)20 7594 6203r.syms

 
 
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Location

 

702Electrical EngineeringSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

370 results found

Syms R, Bouchaala A, 2023, MEMS Electrostatically Driven Coupled Beam Filter Banks., Micromachines (Basel), Vol: 14, ISSN: 2072-666X

MEMS bandpass filters based on electrostatically driven, mechanically coupled beams with in-plane motion have been demonstrated up to the VHF band. Filters higher than second order with parallel plate drives have inherent tuning difficulties, which may be resolved by adding mass-loaded beams to the ends of the array. These beams deflect for DC voltages, and thus allow synchronized electrostatic tuning, but do not respond to in-band AC voltages and hence do not interfere with dynamic synchronization. Additional out-of-band responses may be damped, leaving the desired response. The principle is extended here to close-packed banks of filters, with adjacent arrays sharing mass-loaded beams that localize modes to sub-arrays. The operating principles are explained using a lumped element model (LEM) of the equations of motion in terms of resonant modes and the reflection of acoustic waves at discontinuities. Performance is simulated using the LEM and verified using the more realistic stiffness matrix method (SMM) for banks of up to eight filters. Similar or dissimilar filters may be combined in a compact arrangement, and the method may be extended to higher order resonances and alternative coupled resonator systems.

Journal article

Syms RRA, Kwan FY, Sydoruk O, 2023, Dark field imaging of high aspect ratio structures - a simple model., Opt Express, Vol: 31, Pages: 39279-39291

A simplified model for dark-field optical imaging of three-dimensional high aspect ratio micro- and nano- structures is proposed, to reduce the time taken to simulate object fields with in-plane scattering between different parts of the object. Primary scattering is found by assuming that illumination of Manhattan geometries generates a set of spherical edge waves, following the incremental theory of diffraction. Secondary scattering is found by assuming that primary scattering is re-scattered from nearby features. Diffraction coefficients are simplified, and the number of illuminating beams is limited to those generating waves that enter the objective lens. Images obtained using TE and TM polarizations are compared, and results are benchmarked against a vectorial finite element model. Applications lie in simulating optical inspection of structures containing vertically etched features including MEMS and NEMS.

Journal article

Syms RRA, Wright S, 2023, Solvent-pumped evaporation concentration on paper in linear and radial geometries, BIOMICROFLUIDICS, Vol: 17

Journal article

Sydoruk O, Syms R, Voronov A, 2023, Waveguide antenna topologies for distributed high-frequency near-field communication and localization, IEEE Transactions on Antennas and Propagation, Vol: 71, Pages: 5026-5035, ISSN: 0018-926X

High-frequency near-field communication is an inherently short-range technology. However, the total capture volume can be increased with traveling-wave antennas. Here, we report on analysis, design, and measurements of flexible waveguide antennas and discuss their performance for near-field communication and localization. The antennas comprise sections of coaxial transmission lines loaded periodically with field-generating inductive networks. Several topologies were compared to each other theoretically and the best-performing candidate was selected to fabricate antennas between 5 and 48 meters long, each containing 15 read nodes. Waveguiding properties of the antennas were measured and agreement with theory was demonstrated. Afterwards, each antenna was integrated with a custom NFC reader and shown to be capable of near-field communication with and localization of commercial off-the-shelf transponders compliant with ISO 14443 Type A protocol. The transverse detection range was 10 cm with 1 W input RF power. Both one-dimensional and quasi two-dimensional configurations were tested. The proposed antennas are flexible, scalable, have low loss, and could be used for near-field communication, identification, and tracking of distributed and mobile tags.

Journal article

Syms R, Taylor-Robinson S, Trovato G, 2023, Circular medicine – being mindful of resources and waste recycling in healthcare systems, Risk Management and Healthcare Policy, Vol: 16, Pages: 267-270, ISSN: 1179-1594

In the light of the COP27 Climate Change Conference, the concept of the circular economy has come to the fore with promotion of reuse and recycling of appliances and materials from electronics to clothes. This concept has not been widely taken up by healthcare systems. In this perspective article, we discuss the idea of the circular economy and how, by extension, the concept of “circular medicine” with optimised hospital and medical clinic waste recycling might be promoted in the context of better stewardship of resources in healthcare management.

Journal article

Syms RRA, Wright S, 2023, Paper-based evaporation concentrators: Comparison of linear and radial geometries, Biomicrofluidics, Vol: 17, Pages: 1-12, ISSN: 1932-1058

Paper-based evaporation concentrators with linear and radial geometries are compared. A new method of finding approximate analytic solutions of the advection–dispersion equation is proposed, based on the behavior of concentrators with infinite sources. Analytic approximations are compared with numerical solutions, and the advantage of radial concentration is highlighted: linear concentration rates scale with the square root of the Péclet number Pe while radial rates scale with Pe itself, leading to faster radial concentration beyond a critical value. Experiments are performed with Brilliant Blue FCF dye, using optical transmission and the Beer–Lambert law for quantitation. Dye concentrations are chosen for operation in the linear absorbance regime. Radial concentration is demonstrated under ambient conditions on filter paper disks with 60 mm diameter evaporation areas fed from a perimeter source, in a reverse of the well-known “coffee stain” experiment. Airflow enhanced concentration in strips and wedges is compared directly, using laser-patterned chromatography paper. The advantage of radial concentration is confirmed (and enhanced by diversion of concentrate to the corners of strips) and concentration factors greater than ∼500 (the dynamic range of measurement) are obtained in ∼2 h using 30 mm long columns.

Journal article

Chamadol N, Syms R, Laopaiboon V, Promsorn J, Eurboonyanun Ket al., 2023, New Imaging Techniques., Recent Results Cancer Res, Vol: 219, Pages: 109-145, ISSN: 0080-0015

The chapter discusses the advancement of new imaging techniques, the role of imaging in CCA diagnosis, anatomical and morphological classification, ultrasound screening of CCA, ultrasound findings of MF-CCA, PI-CCA, ID-CCA, the use of CT in CCA diagnosis, staging and treatment planning, CT volumetry and estimation of future liver remnant, post-treatment follow-up and surveillance, MRI imaging, Positron Emission Tomography (PET)/CT, limitations to contrast studies and resolution, internal receivers for CCA imaging, and in vitro imaging of CCA.

Journal article

Syms R, Noorwali A, 2022, Polyphase codes for multiplexed acoustic signalling and sensing on pipes, Smart Materials and Structures, Vol: 31, ISSN: 0964-1726

Transmission of acoustic signals between distributed sensor nodes may be useful for status monitoring of elongated structures such as pipelines. In principle, coded signals can be used in an asynchronous multiplexed system, provided the signals are distinguishable. However, multimode effects complicate signal propagation, so any such codes should be short. A search for polyphase code families with properties suitable for acoustic code division multiple access is presented. Algorithms for reduction of search space to allow use of a laptop for code discovery are described. Short codes of base 6 are shown to outperform codes of bases 2, 3, 4 and sets suitable for systems with 2 and 3 users are identified. The codes have similar properties to Barker codes but larger sidelobes. Their use is demonstrated by simulation and experiment at kHz frequencies using an air-filled copper pipe, an electromagnetic acoustic transducer (EMAT) and a microphone designed to excite and detect the $L\left( {0,1} \right)$ mode. Low loss propagation over 25 m is achieved with a 20 kHz carrier. Excellent agreement between experiment and theory is demonstrated, with performance limited by transducer bandwidth.

Journal article

Syms RRA, Voronov A, Sydoruk O, 2022, HF RFID tag location using magneto-inductive waves, IEEE Journal of Radio Frequency Identification, Vol: 6, Pages: 347-354, ISSN: 2469-7281

Location of passive RFID tags in the HF regime presents significant problems, because of the absence of radiating fields at the low frequencies involved. Here we present a solution for one-dimensional localization based on magneto-inductive (MI) waves. Passive tags are interrogated using a travelling wave antenna based on a MI waveguide, a magnetically coupled array of L−C resonators supporting travelling waves. Load modulation signals generated by the tag during its unique identifier response are coupled into the waveguide and travel to either end with low group velocity. Signal timings are measured by cross-correlation, and the tag position is estimated to the nearest resonant loop from the difference in their arrival times. Correlation detection is demonstrated using a system model, and theoretical predictions are confirmed using an experimental system containing eleven transformer-coupled resonators operating at 13.56 MHz frequency. Accurate localization is obtained up to the tag reading limit using <1W RF power.

Journal article

Voronov A, Syms RRA, Sydoruk O, 2022, High-performance magnetoinductive directional filters, Electronics, Vol: 11, Pages: 1-16, ISSN: 1450-5843

Multiport magnetoinductive (MI) devices with directional filter properties are presented. Design equations are developed and solved using wave analysis and dispersion theory, and it is shown that high-performance directional filters can be realised for use both in MI systems with complex, frequency-dependent impedance and in conventional systems with real impedance. Wave analysis is used to reduce the complexity of circuit equations. High-performance MI structures combining directional and infinite rejection filtering are demonstrated, as well as multiple-passband high-rejection filtering. A new method for improving filtering performance through multipath loss compensation is described. Methods for constructing tuneable devices using toroidal ferrite-cored transformers are proposed and demonstrated, and experimental results for tuneable MI directional filters are shown to agree with theoretical models. Limitations are explored, and power handling sufficient for HF RFID applications is demonstrated, despite the use of ferrite materials.

Journal article

Syms R, Liu D, 2022, Buckling electrothermal NEMS actuators: analytic design for very slender beams, Micro, Vol: 2, Pages: 54-67, ISSN: 2673-8023

Analytic approximations are presented for the response of buckling-mode electrothermal actuators with very slender beams with a width-to-length ratio of W/L≤0.001 of the type found in nanoelectromechanical systems (NEMS). The results are found as closed-form solutions to the Euler beam bending theory rather than by an iterative numerical solution or a time-consuming finite element analysis. Expressions for transverse deflections and stiffness are presented for actuators with the common raised cosine and chevron pre-buckled shapes. The approximations are valid when the effects of bending dominate over those of axial compression. A few higher-order approximations are also presented for less slender beams with 0.001≤W/L≤0.01.

Journal article

Syms R, Bouchaala A, 2021, Mechanical synchronization of MEMS electrostatically driven coupled beam filters, Micromachines, Vol: 12, Pages: 1-12, ISSN: 2072-666X

Micro-electromechanical systems (MEMS) bandpass filters based on arrays of electrostatically driven coupled beams have been demonstrated at MHz frequencies. High performance follows from the high Q-factor of mechanical resonators, and electrostatic transduction allows tuning, matching and actuation. For high-order filters, there is a conflict between the transduction mechanism and the coupling arrangement needed for dynamic synchronization: it is not possible to achieve synchronization and tuning simultaneously using a single voltage. Here we propose a general solution, based on the addition of mass-loaded beams at the ends of the array. These beams deflect for direct current (DC) voltages, and therefore allow electrostatic tuning, but do not respond to in-band alternating current (AC) voltages and hence do not interfere with synchronization. Spurious modes generated by these beams may be damped, leaving a good approximation to the desired response. The approach is introduced using a lumped element model and verified using stiffness matrix and finite element models for in-plane arrays with parallel plate drives and shown to be tolerant of the exact mass value. The principle may allow compensation of fabrication-induced variations in complex filters.

Journal article

Syms R, Sydoruk O, Wiltshire M, 2021, Magneto-inductive HF RFID system, International Journal of Radio Frequency Identification Technology and Applications, Vol: 5, Pages: 148-153, ISSN: 1745-3216

Efforts to increase read range in passive HF RFID systems are hampered by the poor range scaling law of inductive coupling. An alternative approach to enlarging capture volume—increasing the lateral extent of the antenna—is proposed, using a magneto-inductive (MI) travelling wave arrangement to allow larger antenna sizes. A theory of load modulation in MI systems is first presented, together with field simulations in the capture volume. A 2.3 metre-long MI antenna is then constructed, and an active tag emulator is used to demonstrate load modulation. RFID is then demonstrated, with the antenna in both reflection and transmission modes, using a custom reader constructed from laboratory equipment. A transverse read range of 0.5 m is obtained using commercial off-the-shelf RFID cards with 12 W RF power, with high uniformity along the length of the antenna.

Journal article

Voronov A, Sydoruk O, Syms RRA, 2021, Power waves and scattering parameters in magneto-inductive systems, AIP Advances, Vol: 11, ISSN: 2158-3226

Difficulties arise in the definition of power flow in transmission-line systems with a complex propagation constant. These were resolved by Kurokawa using quantities known as “power waves,” which contain both voltage and current terms and correctly separate power flow into forward- and backward-traveling components. Similar difficulties must arise for electromagnetic metamaterials since any discrete, periodic structure leads to band-limited propagation, with a complex propagation constant both inside and outside the bands due to loss and cutoff, respectively. Here, discrete power waves are defined for magneto-inductive (MI) systems, metamaterials based on chains of magnetically coupled LC resonators. These waves are shown to satisfy the discrete power conservation equation for MI waves and are used to calculate scattering parameters for multi-port MI devices without the anomalous predictions of conventional methods. The results will allow correct evaluation of internal scattering parameters in MI systems.

Journal article

Wright S, Syms R, 2021, Shock-free ion transmission in a skimmer-based MEMS mass spectrometer vacuum interface, Journal of Micromechanics and Microengineering, Vol: 31, ISSN: 0960-1317

Shock-free ion transmission from atmospheric pressure to a MEMS-based mass spectrometer has been achieved using micro-engineered nickel skimmers. The signal level has increased 70-fold compared with a previous configuration in which the skimmer did not sample the supersonic flow. The skimmers are formed by electroplating internal surfaces of anisotropically etched, pyramidal holes in (100) silicon. Etching from the reverse of the wafer exposes free- standing, open-ended skimmers supported by remaining silicon. High-resolution schlieren imaging has been used to visualise gas flow within the interface. Signal enhancement and increased gas throughput are observed when the skimmer attaches to the supersonic gas expansion via oblique shocks. The silicon back wall interacts with the flow field, causing the free jet Mach disc to evolve into a bowl-shaped surface shock whose position asymptotically approaches a stand-off separation as the interface pressure decreases. Ideally, the skimmer entrance should be located approximately midway between the inlet and the back wall. This development should allow a sensitivity increase in MEMS mass spectrometers using pumps of moderate capacity.

Journal article

Bouchaala A, Syms R, 2020, New architectures for micromechanical coupled beam array filters, Microsystem Technologies: micro and nanosystems information storage and processing systems, Vol: 27, Pages: 3377-3387, ISSN: 0946-7076

Coupled resonator filters implemented as microelectromechanical systems (MEMS) offer performance advantages as band-pass filters at MHz frequencies. Here new designs based on resonant cavities for acoustic slow waves are developed to allow alternative frequency responses. Derivation of the lumped element model for coupled beam systems with in-plane motion from Rayleigh–Ritz perturbation theory is first reviewed. Departures from ideal behaviour caused by mechanical and electrostatic detuning are resolved. Slow wave theory is then used to develop linear array topologies with novel responses including band-stop and comb filtering with controlled filter roll-off. A systematic procedure is developed to allow rapid identification of design parameters without the need for lengthy numerical simulation, using the lumped element, stiffness matrix and finite element methods to investigate the layout parameters of initial design concepts, detailed mechanical effects and detailed electrostatic effects, respectively. High performance is demonstrated, with good agreement between the models.

Journal article

Syms R, Khuntikeo N, Titapun A, Chamadol N, Boonphongsathien W, Sa-Ngiamwibool P, Taylor-Robinson S, Wadsworth C, Zhang S, Kardoulaki Eet al., 2020, In vitro intraductal MRI and T2 mapping of cholangiocarcinoma using catheter coils, Hepatic Medicine : Evidence and Research, Vol: 2020, Pages: 107-114, ISSN: 1179-1535

Aim: Diagnostic imaging of early-stage cholangiocarcinoma is challenging. A previous in vitro study of fixed-tissue liver resection specimens investigated T2 mapping as a method of exploiting the locally increased signal-to-noise ratio (SNR) of duodenoscope coils for improved quantitative magnetic resonance imaging (MRI), despite their non-uniform sensitivity. This work applies similar methods to unfixed liver specimens using catheter-based receivers.Methods: Ex vivo intraductal MRI and T2 mapping were carried out at 3T on unfixed resection specimens obtained from cholangiocarcinoma patients immediately after surgery using a catheter coil based on a thin-film magneto-inductive waveguide, inserted directly into an intrahepatic duct.Results: Polypoid intraductal cholangiocarcinoma was imaged using fast spin echo sequences. High resolution T2 maps were extracted by fitting of data obtained at different echo times to mono-exponential models, and disease-induced changes were correlated with histopathology. An increase in T2 was found compared with fixed specimens and differences in T2 allowed the resolution of tumour tissue and malignant features such as polypoid morphology.Conclusions: Despite their limited field of view, useful data can be obtained using catheter coils, and T2 mapping offers an effective method of exploiting their local SNR advantage without the need for image correction.

Journal article

Khuntikeo N, Titapun A, Chamadol N, Boonphongsathien W, Sa-Ngiamwibool P, Taylor-Robinson SD, Wadsworth CA, Zhang S, Kardoulaki EM, Young IR, Syms RRet al., 2020, Improving the detection of cholangiocarcinoma: in vitro MRI-based study using local coils and T2 mapping, Hepatic Medicine : Evidence and Research, Vol: 12, Pages: 29-39, ISSN: 1179-1535

Aim: Cholangiocarcinoma is endemic in southeast Asia, generally developing from liver fluke infestation. However, diagnostic imaging of early-stage disease is challenging. The aim of this work is to investigate relaxometry (specifically, T2 mapping) as a method of exploiting the higher signal-to-noise ratio (SNR) of internal coils for improved reception of magnetic resonance signals, despite their non-uniform sensitivity.Methods: Ex vivo T2 mapping was carried out at 3T on fixed resection specimens from Thai cholangiocarcinoma patients using an mGRASE sequence and an endoscope coil based on a thin-film magneto-inductive waveguide and designed ultimately for internal use.Results: Disease-induced changes including granulomatous inflammation, intraepithelial neoplasia and intraductal tumours were correlated with histopathology, and relaxation data were compared with mono- and bi-exponential models of T2 relaxation. An approximately 10-fold local advantage in SNR compared to a 16-element torso coil was demonstrated using the endoscope coil, and improved tissue differentiation was obtained without contrast agents.Conclusion: The performance advantage above follows directly from the inverse relation between the component of the standard deviation of T2 due to thermal noise and the SNR, and offers an effective method of exploiting the SNR advantage of internal coils. No correction is required, avoiding the need for tracking, relaxing constraints on coil and slice orientation and providing rapid visualization.

Journal article

Alsaleh M, Barbera TA, Andrews RH, Sithithaworn P, Khuntikeo N, Loilome W, Yongvanit P, Cox IJ, Syms RRA, Holmes E, Taylor-Robinson SDet al., 2019, Mass spectrometry: A guide for the clinician, Journal of Clinical and Experimental Hepatology, Vol: 9, Pages: 597-606, ISSN: 0973-6883

Metabolic profiling, metabonomics and metabolomics are terms coined in the late 1990s as they emerged as the newest ‘omics’ technology at the time. This line of research enquiry uses spectroscopic analytical platforms, which are mainly nuclear magnetic resonance spectroscopy and mass spectrometry (MS), to acquire a snapshot of metabolites, the end products of a complex biological system. Metabolic profiling enables the detection, quantification and characterisation of metabolites in biofluids, cells and tissues. The source of these compounds can be of endogenous, microbial or exogenous origin, such as dietary or xenobiotic. This results in generating extensive, multivariate spectroscopic data that require specific statistical manipulation, typically performed using chemometric and pattern recognition techniques to reduce its dimensions, facilitate its biological interpretation and allow sample classification and biomarker discovery. Consequently, it is possible to study the dynamic metabolic changes in response to disease, intervention or environmental conditions. In this review, we describe the fundamentals of MS so that clinicians can be literate in the field and are able to interrogate the right scientific questions.

Journal article

Syms RRA, Sydoruk O, Bouchaala A, 2019, Improved optical imaging of high aspect ratio nanostructures using dark-field microscopy, Nanotechnology, Vol: 30, ISSN: 0957-4484

Improvements to white light optical imaging of widely spaced, high aspect ratio nanostructures are demonstrated using dark-field field microscopy. 1D models of bright- and dark-field imaging are developed from rigorous modal diffraction theory by assuming that features are periodic. A simple model is developed to explain dark field results and simulated line images obtained using the two modalities are compared for different dimensions and materials. Increased contrast between etched features and the substrate is demonstrated in dark field, due to its reduced sensitivity to scattering from flat areas. The results are verified using silicon nanostructures fabricated by sidewall transfer lithography, and feature separation with improved tolerance to apparent substrate brightness is demonstrated during image segmentation using the Otsu method.

Journal article

Alsaleh M, Leftley Z, Barbera T, Sithithaworn P, Khuntikeo N, Loilome W, Yongvanit P, Cox IJ, Chamadol N, Syms R, Andrews R, Taylor-Robinson Set al., 2018, Cholangiocarcinoma: a guide for the nonspecialist, International Journal of General Medicine, Vol: 12, Pages: 13-23, ISSN: 1178-7074

Cholangiocarcinoma (CCA) is a tumor with increasing prevalence around the world. The prevalence of CCA is highest in East Asia and most significantly in the countries through which the Mekong River flows, owing to the presence of liver flukes, which are consumed in raw fish dishes. Outside Asia, the causes of bile duct cancers for the most part are unknown. In this review, we assess the current state of knowledge in both fluke-associated and sporadic CCA, from etiological, diagnostic, and treatment perspectives.

Journal article

Syms RRA, Bouchaala A, Sydoruk O, Liu Det al., 2018, Optical imaging and image analysis for high aspect ratio NEMS, Journal of Micromechanics and Microengineering, Vol: 29, ISSN: 0960-1317

A strategy for optical microscopy of high-aspect-ratio (HAR) nanoelectromechanical systems (NEMS) that combine large feature spacing and large height with sub-wavelength width is presented. Line images are simulated using a 2D model of incoherent imaging based on modal diffraction theory. Beyond a sufficient depth, it is shown that sub-wavelength features appear as dark lines, while wider features are visible as their edges. The results suggest NEMS and MEMS may be separated from background in images by detection of valleys in brightness. Results are confirmed by imaging of Si NEMS containing 100 nm wide features in a bright-field microscope. Algorithms for separation of NEMS, MEMS and background in microscope images based on valley detection, thresholding and masking are demonstrated.

Journal article

Wright S, Syms RRA, 2018, Supersonic jet interactions with a micro-engineered skimmer, Journal of Micromechanics and Microengineering, Vol: 28, ISSN: 0960-1317

A micro-engineered, skimmer-based vacuum interface has been demonstrated and used to investigate gas dynamics on a sub-millimeter length scale. The interface is fabricated as a stacked assembly of silicon dies, based on an anisotropically etched inlet orifice and a pyramidal skimmer cone formed in electroplated nickel. Expansion of gas into vacuum, interaction of a supersonic jet with the skimmer and transmission of a collimated beam into a second vacuum stage have all been imaged with a schlieren microscope. Using a glass-walled vacuum chamber, flow patterns upstream and fully downstream of the skimmer have been imaged together for the first time. At low first-stage pressures, the 150–200 µm tall skimmers cannot fully penetrate the shock arising from interaction of the jet with the back wall. However, as the pressure is increased, a multiple shock cell structure evolves, the jet narrows and transmission rises sharply. Eventually, a collimated beam is transmitted to the second stage. When the skimmer aperture is smaller than the source aperture, a series of distinct peaks is evident in a plot of transmission against first-stage pressure. Imaging shows that at each successive peak, the number of shock cells increases by one and the skimmer inlet is coincident with a node.

Journal article

Wiltshire MCK, Syms RRA, 2018, Measuring noise in microwave metamaterials, JOURNAL OF APPLIED PHYSICS, Vol: 123, ISSN: 0021-8979

Electromagnetic metamaterials are artificially constructed media composed of arrays of electrical circuits that can exhibit electric and magnetic characteristics unlike those of any conventional materials. However, the materials are lossy and hence noisy, so that the signal-to-noise ratio in practical situations is greatly reduced. In particular, operating in the double negative region, where both the permittivity and the permeability are negative so that the refractive index is real but negative, incurs significant loss and noise penalties. In this work, we report noise measurements on a double negative metamaterial at microwave frequencies and compare them with the results of a simple model based on a transmission line loaded with lossy elements that mimic the split ring resonators and fine wires of the metamaterial. A noise source is associated with the resistive part of each element, and these are added incoherently to predict the total noise spectrum of the metamaterial. The theoretical results are in good agreement with the measurements. In particular, we find that the measured noise spectrum has contributions from both electric and magnetic noise, but is dominated by the magnetic noise. This limits possible applications, even with optimised materials, to functions that cannot be realised by conventional means.

Journal article

Kamel H, Syms RRA, Kardoulaki EM, Rea Met al., 2018, Surgical wound monitoring by MRI with a metamaterial-based implanted local coil, EPJ Applied Metamaterials, Vol: 5, ISSN: 2272-2394

An implantable sensor for monitoring surgical wounds after bowel reconstruction is proposed. The sensor consists of a coupled pair of 8-element magneto-inductive ring resonators, designed for mounting on a biofragmentable anastomosis ring to give a local increase in signal-to-noise ratio near an annular wound during 1H magnetic resonance imaging. Operation on an anti-symmetric spatial mode is used to avoid coupling to the B1 field during excitation, and a single wired connection is used for MRI signal output. The electrical response and field-of-view are estimated theoretically. Prototypes are constructed from flexible elements designed for operation at 1.5 T, electrical responses are characterized and local SNR enhancement is confirmed using agar gel phantoms.

Journal article

Syms RRA, Young IR, Solymar L, 2018, Metamaterial Catheter Receivers for Internal Magnetic Resonance Imaging, WORLD SCIENTIFIC HANDBOOK OF METAMATERIALS AND PLASMONICS, VOL 1: ELECTROMAGNETIC METAMATERIALS, Editors: Maier, Shamonina, Publisher: WORLD SCIENTIFIC PUBL CO PTE LTD, Pages: 471-497, ISBN: 978-981-3227-62-0

Book chapter

Syms RRA, Kardoulaki E, Rea M, Choonee K, Taylor-Robinson S, Wadsworth C, Young IRet al., 2017, Magneto-inductive magnetic resonance imaging duodenoscope, Progress in Electromagnetics Research (PIER), Vol: 159, Pages: 125-138, ISSN: 1070-4698

A magnetic resonance imaging (MRI) duodenoscope is demonstrated, by combining non-magnetic endoscope components with a thin-film receiver based on a magneto-inductive waveguide.The waveguide elements consist of figure-of-eight shaped inductors formed on either side of a flexiblesubstrate and parallel plate capacitors that use the substrate as a dielectric. Operation is simulatedusing equivalent circuit models and by computation of two- and three-dimensional sensitivity patterns.Circuits are fabricated for operation at 127.7 MHz by double-sided patterning of copper-clad Kaptonand assembled onto non-magnetic flexible endoscope insertion tubes. Operation is verified by benchtesting and by1H MRI at 3T using phantoms. The receiver can form a segmented coaxial image alongthe length of the endoscope, even when bent, and shows a signal-to-noise-ratio advantage over a surfacearray coil up to three times the tube diameter at the tip. Initial immersion imaging experiments havebeen carried out and confirm an encouraging lack of sensitivity to RF heating.

Journal article

Syms RRA, Kardoulaki E, Rea M, Taylor-Robinson S, Wadsworth C, Young IRet al., 2017, Metamaterial Magnetic Resonance Imaging Endoscope, 2017 11th International Congress on Engineered Material Platforms for Novel Wave Phenomena (METAMATERIALS), Publisher: IEEE, Pages: 337-339

Conference paper

Kamel H, Syms R, Kardoulaki EM, Rea Met al., 2017, Metamaterial MRI-based Surgical Wound Monitor, 2017 11th International Congress on Engineered Material Platforms for Novel Wave Phenomena (METAMATERIALS), Publisher: IEEE, Pages: 334-336

Conference paper

Syms R, 2017, Rapid evaporation-driven chemical pre-concentration and separation on paper., Biomicrofluidics, Vol: 11, ISSN: 1932-1058

Airflow-enhanced evaporation is investigated as a method for rapid chemical preconcentration on a thin porous substrate. The mechanism is described by combining 1D models of capillary rise, chromatography, and pervaporation concentration. It is shown that the effective length of the column can be shorter than its actual length, allowing concentrate to be held at a stagnation point and then released for separation, and that the Péclet number, which determines the concentration performance, is determined only by the substrate properties. The differential equations are solved dynamically, and it is shown that faster concentration can be achieved during capillary filling. Experiments are carried out using chromatography paper in a ducted airflow, and concentration is quantified by optical imaging of water-soluble food dyes. Good agreement with the model is obtained, and concentration factors of ≈100 are achieved in 10 min using Brilliant Blue FCF. Partial separation of Brilliant Blue from Tartrazine is demonstrated immediately following concentration, on a single unpatterned substrate. The mechanism may provide a method for improving the sensitivity of lab-on-paper devices.

Journal article

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