Stephen J. Matcher

The University of Sheffield, Sheffield, England, United Kingdom

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Publications (87)119.89 Total impact

  • X. Liu, D. Gad, Z. Lu, R. Lewis, M. Carre, S. Matcher
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    ABSTRACT: This paper describes three series of tests that were designed to investigate how skin mechanical and structural properties, measured using a ‘Cutometer’ and optical coherence tomography, affect the frictional behaviour of human finger-pads. First, the skin mechanical properties across all fingers and the palm in participants’ dominant hands were assessed. Results showed that the distensibility of skin (total deformation in a suction test) is associated with stratum corneum thickness and that this in turn affects friction (thicker stratum corneum leads to higher friction), giving a link between distensibility and friction. Tape stripping to remove the superficial layer of the skin led to increased moisture (and/or electric charge on the skin surface) that led to higher friction. No accompanying changes were seen in structural properties, so it was concluded that moisture was the main cause of the adhesion increase. More work is required to isolate moisture and possible changes in electric charge using alternative measurement techniques. When rubbing with sand-paper, the stratum corneum thinned considerably and friction reduced. Moisture was ruled out as a cause of friction changes in this instance. Skin normal stiffness also did not change, but lateral stiffness changes have been seen in previous work when the stratum corneum thickness has been reduced, so this is likely to be the cause of the reduced friction. This will be investigated further in future work using dynamic optical coherence tomography measurements.
    ARCHIVE Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology 1994-1996 (vols 208-210) 02/2015; 229(3). DOI:10.1177/1350650114567699 · 0.66 Impact Factor
  • Stephen J Matcher
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    ABSTRACT: Connective tissues such as articular cartilage have been the subject of study using novel optical techniques almost since the invention of polarized light microscopy (PLM). Early studies of polarized light micrographs were the main evidential basis for the establishment of quantitative models of articular cartilage collagen structure by Benninghoff and others. Even now, state of the art optical techniques including quantitative polarized light microscopy (qPLM), optical coherence tomography (OCT), polarization-sensitive optical coherence tomography (PS-OCT), second harmonic generation (SHG) microscopy, Fourier-transform infrared (FTIR) microscopy, Raman and optical hyperspectral reflectance and fluorescence imaging are providing new insights into articular cartilage structure from the nanoscale through to the mesoscale. New insights are promised by emerging modalities such as optical elastography. This short review highlights some key recent results from modern optical techniques.
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    Zenghai Lu, Deepa Kasaragod, Stephen J Matcher
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    ABSTRACT: We report on a new articular cartilage imaging technique with potential for clinical arthroscopic use, by supplementing the variable-incidence-angle polarization-sensitive optical coherence tomography method previously developed by us with a conical beam scan protocol. The technique is validated on bovine tendon by comparing experimental data with simulated data generated using the extended Jones matrix calculus. A unique capability of this new optical technique is that it can locate the "brushing direction" of collagen fibers in articular cartilage, which is structural information that extends beyond established methods such as split-line photography or birefringent fast-axis measurement in that it is uniquely defined over the full azimuthal-angle range of (-π, + π). The mapping of this direction over the cartilage surface may offer insights into the optimal design of tissue-engineering scaffolds for cartilage repair.
    Biomedical Optics Express 03/2014; 5(3):752-62. DOI:10.1364/BOE.5.000752 · 3.50 Impact Factor
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    ABSTRACT: The biological and mechanical function of connective tissues is largely determined by controlled cellular alignment and therefore it seems appropriate that tissue-engineered constructs should be architecturally similar to the in vivo tissue targeted for repair or replacement. Collagen organisation dictates the tensile properties of most tissues and so monitoring the deposition of cell-secreted collagen as the construct develops is essential for understanding tissue formation. In this study, electrospun fibres with a random or high degree of orientation, mimicking two types of tissue architecture found in the body, were used to culture human fibroblasts for controlling cell alignment. The minimally-invasive technique of second harmonic generation was used with the aim of monitoring and profiling the deposition and organisation of collagen at different construct depths over time while construct mechanical properties were also determined over the culture period. It was seen that scaffold fibre organisation affected cell migration and orientation up to 21 days which in turn had an effect on collagen organisation. Collagen in random fibrous constructs was deposited in alternating configurations at different depths however a high degree of organisation was observed throughout aligned fibrous constructs orientated in the scaffold fibre direction. Three-dimensional second harmonic generation images showed that deposited collagen was more uniformly distributed in random constructs but aligned constructs were more organised and had higher intensities. The tensile properties of all constructs increased with increasing collagen deposition and were ultimately dictated by collagen organisation. This study highlights the importance of scaffold architecture for controlling the development of well-organised tissue engineered constructs and the usefulness of second harmonic generation imaging for monitoring collagen maturation in a minimally invasive manner.
    PLoS ONE 02/2014; 9(2):e89761. DOI:10.1371/journal.pone.0089761 · 3.53 Impact Factor
  • P. Khoo, S. Mittar, D. Kasaragod, Z. Lu, S. J. Matcher
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    ABSTRACT: Cervical cancer is the eleventh most common cancer in the UK, especially for women under 35. In developed countries, cervical cancer is diagnosed by performing colposcopy. Contrast is enhanced by spraying dilute acetic acid onto the surface of the tissue. In the past decades, it has been shown that abnormal cervical epithelium turns opaque white upon contact with this weak acid whereas normal epithelium is generally not affected. This mechanism is known as aceto-whitening. However, the exact mechanism of this phenomenon is not fully known. In this study, OCT using near infrared light was used to quantify depth-resolved kinetics of aceto-whitening in a simple squamous epithelium model: rabbit cornea. We have found that both the epithelium and stroma brighten with approximately the same time course, reaching a peak reflectivity at about 50 seconds. The most significant increase in reflectivity was seen in the first 20 seconds upon the application of acid, and was measured to be 11dB. This result is compared with phosphate buffered saline solution, which was shown to exhibit no effect. Lactic acid, an alpha-hydroxy acid, has been reported as a negative control for aceto-whitening. However, our OCT results showed a significant epithelial brightening effect of approximately 8 dB in the first 20 seconds. The key difference with acetic acid is the lack of brightening in the corneal stroma. This could be due to inability to permeate through the basal lamina between corneal epithelium and stroma or lack of interaction with stromal keratocytes.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2014; DOI:10.1117/12.2036021 · 0.20 Impact Factor
  • Zenghai Lu, Deepa Kasaragod, Stephen J. Matcher
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    ABSTRACT: A new imaging technique is presented by introducing the concept of conical scan to the variable-incidenc-angle polarimetry (VIA) previously developed by our group. The technique would facilitate the translating of the VIA technique to the clinic by simplifying the requirements of measurements in two orthogonal planes by using a conical scan protocol. Conical scan PS-OCT images could illustrate directly the azimuthal angle of the collage fibers in birefringent tissue, which was validated by measurements on a bovine tendon. We have showed the unique technique can be used to locate the "brushing direction" of collagen fibers in articular cartilage. Measuring this direction over the cartilage surface could potentially help designing of tissue-engineering scaffolds for cartilage repair.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2014; DOI:10.1117/12.2036731 · 0.20 Impact Factor
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    Kin Man Au, Zenghai Lu, Stephen J Matcher, Steven P Armes
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    ABSTRACT: Optical coherence tomography (OCT) is a modern high resolution subsurface medical imaging technique. Herein we describe: (i) the synthesis of a thiophene-functionalized oligo(ethylene glycol) methacrylate (OEGMA)-based statistical copolymer, denoted poly(2TMOI-OEGMA); (ii) the preparation of sterically-stabilized polypyrrole (PPy) nanoparticles of approximately 60 nm diameter; (iii) the evaluation of these nanoparticles as a NIR-absorbing optical contrast agent for high-resolution OCT imaging. We show that poly(2TMOI-OEGMA)-stabilized PPy nanoparticles exhibit similar optical properties to poly(vinyl alcohol) (PVA)-stabilized PPy nanoparticles of comparable size prepared using commercially available PVA. Spectroscopic measurements and Mie calculations indicate that both types of PPy nanoparticles strongly absorb NIR radiation above 1000 nm, suggesting their potential use as OCT contrast agents. In vitro OCT studies indicate that both types of PPy nanoparticles reduce NIR backscattering within homogeneous intralipid tissue phantoms, offering almost identical contrast performance in this medium. However, PVA-stabilized PPy nanoparticles became colloidally unstable when dispersed in physiological buffer and immersed in a solid biotissue phantom and hence failed to generate a strong contrast effect. In contrast, the poly(2TMOI-OEGMA)-stabilized PPy nanoparticles remained well-dispersed and hence exhibited a strong rapid onset contrast effect within the biotissue phantom under identical physiological conditions. Ex vivo studies performed on excised chicken and porcine skin tissue demonstrated that topical administration of a low concentration of poly(2TMOI-OEGMA)-stabilized PPy nanoparticles rapidly enhances OCT image contrast in both cases, allowing key tissue features to be readily identified.
    Biomaterials 08/2013; 34(35). DOI:10.1016/j.biomaterials.2013.07.094 · 8.31 Impact Factor
  • X. Liu, Z. Lu, R. Lewis, M. J. Carre, S. J. Matcher
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    ABSTRACT: This paper presents work using an in vivo technique, optical coherence tomography (OCT), to investigate the structure of human finger pad skin and the influences of some related parameters on skin friction, such as contact area, deformation and hydration. The experimental results show that there was no significant relationship between the thickness of the stratum corneum (SC) and the friction coefficient as well as the number of sweat ducts (SD). The real contact length was found to increase with increasing the applied normal force following the power law of A∝aWA∝Wa. The study of hydration found an increasing linear relationship between the SC moisture and the friction coefficient (up to 72 au).
    Tribology International 07/2013; 63:34–44. DOI:10.1016/j.triboint.2012.08.020 · 2.12 Impact Factor
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    ABSTRACT: The effects on skin of two commercially available topical creams for the treatment of eczema are quantitatively studied using optical coherence tomography. An archetypal corticosteroid (Betamethasone valerate) is compared with a nonsteroidal anti-inflammatory drug (Tacrolimus monohydrate) via left/right comparisons of the epidermal thickness of volar forearm skin on selected volunteers, at baseline and after 14 days of treatment. In 3 of 4 subjects we confirmed previous observations that corticosteroids produce pronounced physical thinning of the epidermis over timescales of a few weeks. In 3 of 4 subjects we further found that Tacrolimus produced no change in epidermal thickness. In one of 4 subjects we found evidence that the epidermis was actually thickened following treatment using Tacrolimus.
    Conference on Photonic Therapeutics and Diagnostics IX; 03/2013
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    ABSTRACT: We report on a photothermal modulation detection scheme developed using a swept source-based optical coherence tomography (OCT) system centred at 1300nm. Photothermal detection is an improved technique for studying the contrast properties of exogenous contrast agents such as highly absorbing polypyrrole (PPy) nanoparticles used for OCT imaging. The swept source based OCT system has a wavelength sweep rate of 10 kHz which is used for the phase modulation detection of various concentrations of PPy nanoparticles. PPy nanoparticles have been recently reported to be a promising candidate for OCT imaging owing to their strong NIR absorption from 700–1300nm. Phase-sensitive detection of the photothermal modulation signal is achieved using a pumped 975 nm laser beam at 80Hz and 160Hz for varying concentrations of PPy nanoparticles dispersed in 2% Intralipid phantom. A phase-sensitive detection system is realised by carrying out the phase calibration using the back reflections obtained from the coverslip used with the sample. This study provides quantitative support for the use of PPy nanoparticles as a potential biocompatible contrast agent in OCT imaging.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2013; 85960:85960R. DOI:10.1117/12.2004024 · 0.20 Impact Factor
  • Zenghai Lu, Stephen J. Matcher
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    ABSTRACT: We report on a new calibration technique that permits the accurate extraction of sample Jones matrix and hence fast-axis orientation by using fiber-based polarization-sensitive optical coherence tomography (PS-OCT) that is completely based on non polarization maintaining fiber such as SMF-28. In this technique, two quarter waveplates are used to completely specify the parameters of the system fibers in the sample arm so that the Jones matrix of the sample can be determined directly. The device was validated on measurements of a quarter waveplate and an equine tendon sample by a single-mode fiber-based swept-source PS-OCT system.
    Proceedings of SPIE - The International Society for Optical Engineering 01/2013; DOI:10.1117/12.2000543 · 0.20 Impact Factor
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    ABSTRACT: This paper highlights the extended Jones matrix calculus based multi-angle study carried out to understand the depth dependent structural orientation of the collagen fibers in articular cartilage using polarization-sensitive optical coherence tomography (PS-OCT). A 3D lamellar model for the collagen fiber orientation, with a quadratic profile for the arching of the collagen fibers in transitional zone which points towards an ordered arrangement of fibers in that zone is the basis of the organization architecture of collagen fibers in articular cartilage. Experimental data for both ex-vivo bovine fetlock and human patellar cartilage samples are compared with theoretical predictions, with a good quantitative agreement for bovine and a reasonable qualitative agreement for human articular cartilage samples being obtained
    Proceedings of SPIE - The International Society for Optical Engineering 01/2013; DOI:10.1117/12.2006831 · 0.20 Impact Factor
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    ABSTRACT: We report a comparison of different capping materials on the intermixing of modulation p-doped InAs/In(Ga)As quantum dots (QD). QD materials with different caps are shown to exhibit significant difference in their optical properties during the annealing process. The selective area intermixing technique is demonstrated to laterally integrate two and three different QD light emitting devices with a single electrical contact. A spectral bandwidth of 240nm centered at 1188nm is achieved in a device with two sections. By calculating the point spread function for the obtained emission spectra, and applying the Rayleigh criteria for resolution, an axial resolution of 3.5μm is deduced. A three section device realizes a spectral bandwidth of 310nm centered at 1145nm. This corresponds to an axial resolution of 2.4μm. Such a small predicted axial resolution is highly desirable in optical coherence tomography system and other coherence-based systems applications.
    Optics Express 11/2012; 20(24):26950-7. DOI:10.1364/OE.20.026950 · 3.53 Impact Factor
  • Zenghai Lu, Stephen J Matcher
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    ABSTRACT: We report on a new calibration technique that permits the accurate extraction of sample Jones matrix and hence fast-axis orientation by using fiber-based polarization-sensitive optical coherence tomography (PS-OCT) that is completely based on non-polarization-maintaining fiber such as SMF-28. In this technique, two quarter-wave plates (QWPs) are used to completely specify the parameters of the system fibers in the sample arm so that the Jones matrix of the sample can be determined directly. The device was validated on measurements of a QWP and an equine tendon sample by a single-mode fiber-based swept-source PS-OCT system.
    Optics Letters 06/2012; 37(11):1931-3. DOI:10.1364/OL.37.001931 · 3.18 Impact Factor
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    ABSTRACT: We report results to verify a theoretical framework to analyze the 3D depth-wise structural organization of collagen fibers in articular cartilage using polarization-sensitive optical coherence tomography. Apparent birefringence data obtained from multi-angle measurements using a time domain polarization-sensitive optical coherence tomography system has been compared with simulated data based on the extended Jones matrix calculus. Experimental data has been shown to agree with the lamellar model previously proposed for the cartilage microstructure based on scanning electron microscopy data. This tool could have potential application in mapping the collagen structural orientation information of cartilage non-invasively during arthroscopy.
    Biomedical Optics Express 03/2012; 3(3):378-87. DOI:10.1364/BOE.3.000378 · 3.50 Impact Factor
  • Zenghai Lu, Deepa K Kasaragod, Stephen J Matcher
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    ABSTRACT: We demonstrate theoretically and experimentally that the phase retardance and relative optic-axis orientation of a sample can be calculated without prior knowledge of the actual value of the phase modulation amplitude when using a polarization-sensitive optical coherence tomography system based on continuous polarization modulation (CPM-PS-OCT). We also demonstrate that the sample Jones matrix can be calculated at any values of the phase modulation amplitude in a reasonable range depending on the system effective signal-to-noise ratio. This has fundamental importance for the development of clinical systems by simplifying the polarization modulator drive instrumentation and eliminating its calibration procedure. This was validated on measurements of a three-quarter waveplate and an equine tendon sample by a fiber-based swept-source CPM-PS-OCT system.
    Journal of Biomedical Optics 03/2012; 17(3):030504. DOI:10.1117/1.JBO.17.3.030504 · 2.75 Impact Factor
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    ABSTRACT: In this work the use of two identical QD SOAs to enhance the performance of swept laser system for OCT applications is discussed, resulting in an increase in bandwidth up to 94nm. The combination of GaAs based QD SOAs and InP based QW SOAs for realizing broad bandwidth sources for OCT system is described. For the swept laser source a 154nm spectral bandwidth from 1193nm to 1347nm and an average power of 8mW is obtained and for the filtered ASE source a 225 nm bandwidth is demonstrated.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2012; DOI:10.1117/12.907977 · 0.20 Impact Factor
  • Zenghai Lu, Deepa K. Kasaragod, Stephen J. Matcher
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    ABSTRACT: We demonstrate theoretically and experimentally that the phase retardance and relative optic-axis orientation of a sample can be calculated without prior knowledge of the actual value of the phase modulation amplitude when using a polarization-sensitive optical coherence tomography system based on continuous polarization modulation (CPM-PS-OCT). We also demonstrate that the sample Jones matrix can be calculated at any values of the phase modulation amplitude in a reasonable range depending on the system effective signal-to-noise ratio. This has fundamental importance for the development of clinical systems by simplifying the polarization modulator drive instrumentation and eliminating its calibration procedure. This was validated on measurements of a three-quarter waveplate and an equine tendon sample by a fiber-based swept-source CPM-PS-OCT system.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2012; DOI:10.1117/12.911457 · 0.20 Impact Factor
  • Deepa K. Kasaragod, Zenghai Lu, Stephen J. Matcher
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    ABSTRACT: The difference in the genetic make up of the constituent molecules in collagen fibers in tendon and articular cartilage is what makes them mechanically and functionally different. A comparative study carried out on the differences in the angle-resolved back-scattering properties obtained from optical coherence tomography based studies on the two different types of scatterers: collagen I and collagen II fibers in bovine tendon and bovine articular cartilage sample, respectively, is reported here. Tendon sample shows greater anisotropy in the angle-resolved scattering profile compared to that obtained from articular cartilage sample. Rayleigh-Gans scattering approximation is used to provide the qualitative support needed to substantiate differences in the light scattering profiles obtained from the two tissues based on the size and type of the scatterers involved.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2012; DOI:10.1117/12.908615 · 0.20 Impact Factor
  • Kin Man Au, Zenghai Lu, Stephen J Matcher, Steven P Armes
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    ABSTRACT: A near-infrared (NIR) absorbing contrast agent based on polypyrrole nanoparticles is described. Quantitative optical coherence tomography studies on tissue phantoms and Mie scattering calculations indicate their potential application for early-stage cancer diagnosis.
    Advanced Materials 12/2011; 23(48):5792-5. DOI:10.1002/adma.201103190 · 15.41 Impact Factor

Publication Stats

561 Citations
119.89 Total Impact Points

Institutions

  • 2007–2014
    • The University of Sheffield
      • Department of Materials Science and Engineering
      Sheffield, England, United Kingdom
    • The Peninsula College of Medicine and Dentistry
      Plymouth, England, United Kingdom
  • 2002–2009
    • University of Exeter
      Exeter, England, United Kingdom