Proceedings Volume 10058

Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications XVII

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Proceedings Volume 10058

Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications XVII

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Volume Details

Date Published: 25 April 2017
Contents: 12 Sessions, 28 Papers, 22 Presentations
Conference: SPIE BiOS 2017
Volume Number: 10058

Table of Contents

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Table of Contents

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  • Front Matter: Volume 10058
  • A tribute to Ron Waynant
  • Optical Fibers and Sensors I
  • Keynote
  • Optical Fibers and Sensors II
  • Optical Fibers and Sensors III
  • Optical Fibers and Sensors IV
  • Optical Fibers and Sensors V
  • Optical Fibers and Sensors VI
  • Optical Fibers and Sensors VII
  • Optical Fibers and Sensors VIII
  • Poster Session
Front Matter: Volume 10058
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Front Matter: Volume 10058
This PDF file contains the front matter associated with SPIE Proceedings Volume 10058, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.
A tribute to Ron Waynant
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A tribute to Dr. Ron W. Waynant (Conference Presentation)
Israel Gannot, Ilko K. Ilev, Juanita J. Anders, et al.
Ron, our beloved mentor, friend and colleague has passed away on May 7th, 2016. This presentation will follow his life and remarkable achievements. It will describe his work and original developments in three major fields of his interest: his early inventive work on vacuum ultraviolet laser radiation; specialty fiber-optics for laser transmission, especially high-power short-pulse broadband laser delivery of free-electron laser; and up to his latest work on Photobiomodulation. The authors will share their personal experience working with Ron - a Nobel and creative person, however, very humble.
Optical Fibers and Sensors I
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Fiber optic tracheal detection device
Brian E. Souhan, Corinne D. Nawn, Richard Shmel, et al.
Poorly performed airway management procedures can lead to a wide variety of adverse events, such as laryngeal trauma, stenosis, cardiac arrest, hypoxemia, or death as in the case of failed airway management or intubation of the esophagus. Current methods for confirming tracheal placement, such as auscultation, direct visualization or capnography, may be subjective, compromised due to clinical presentation or require additional specialized equipment that is not always readily available during the procedure. Consequently, there exists a need for a non-visual detection mechanism for confirming successful airway placement that can give the provider rapid feedback during the procedure. Based upon our previously presented work characterizing the reflectance spectra of tracheal and esophageal tissue, we developed a fiber-optic prototype to detect the unique spectral characteristics of tracheal tissue. Device performance was tested by its ability to differentiate ex vivo samples of tracheal and esophageal tissue. Pig tissue samples were tested with the larynx, trachea and esophagus intact as well as excised and mounted on cork. The device positively detected tracheal tissue 18 out of 19 trials and 1 false positive out of 19 esophageal trials. Our proof of concept device shows great promise as a potential mechanism for rapid user feedback during airway management procedures to confirm tracheal placement. Ongoing studies will investigate device optimizations of the probe for more refined sensing and in vivo testing.
Ion-selective optical sensor for continuous on-line monitoring of dialysate sodium during dialysis
Manoj K. Sharma, Arjan J. H. Frijns, Rajesh Mandamparambil, et al.
Patients with end stage renal disease are dependent on dialysis. In most outpatient centers, the dialysate is prepared with a fixed electrolyte concentration without taking into account the inter-individual differences of essential electrolytes (sodium, potassium and calcium). This one-size fits all approach can lead to acute and chronic cardiovascular complications in dialysis patients. On-line monitoring of these essential electrolytes is an important physiological step towards patient specific dialysate leading to individualized treatment. Currently, changes in electrolyte concentrations are indirectly measured by conductivity measurements, which are not ion- specific. In this paper, we present a novel optical sensor for on-line monitoring of sodium concentrations in dialysate. This sensor is ion-specific and can detect up to a single ion. The working principle is based on the selective fluorescence quenching of photo-induced electron transfer (PET) molecules. The PET molecules when complexed with sodium ions start fluorescing upon laser excitation. The emission intensity is directly correlated to the sodium concentration. To prove the working principle, a micro-optofluidic device has been fabricated in polydimethylsiloxane (PDMS) with integrated optical fibers for fluorescence light collection. The PET molecules are covalently grafted in the PDMS microchannel for continuous monitoring of the sodium dialysate concentrations. The experimental setup consists of a laser module (λ=450nm) operating at 4.5mW, a syringe pump to precisely control the sample flow and a spectrometer for fluorescence collection. The performance of the sensor has been evaluated for sodium ions ranging from 0-50mM. A clear signal and good response time was observed.
New fiber-based approaches for optical biopsy (Conference Presentation)
Jessie R. Weber, Christophe Rivière, Antoine Proulx, et al.
Optical biopsy of tissue using fiber optic probes has proven to be a powerful tool for non-invasive and minimally invasive diagnostics. However, there are still many challenges to improving diagnostic value and commercial translation of these techniques. Many fiber-based methods are limited by background noise, which impairs sensitivity and specificity. Aspects of quality control, such as adequacy of the target of interest sampled and validation of optical measurements with histopathology can be problematic. Complexity, cost, and disposability or sterilizability are roadblocks to widespread clinical use. Here, we present new approaches to using fibers for optical biopsy aimed at solving these problems. Specifically, the new concepts are designed with the goals of being simple and disposable, to improve control of light delivery and collection from the sample, and to inherently enable better quality control of the biopsy process. A concept-of-operation aimed at nearly zero impact to the work flow of the biopsy and standard pathology procedures will be outlined. Several concepts for fiber implementations will be presented. A trade-off analysis of the concepts used to select a first implementation for testing will be presented. Preliminary experimental validation in phantoms and tissue samples will be presented for the selected configuration.
Ultraviolet spectroscopic breath analysis using hollow-optical fiber as gas cell
T. Iwata, T. Katagiri, Y. Matsuura
For breath analysis on ultraviolet absorption spectroscopy, an analysis system using a hollow optical fiber as gas cell is developed. The hollow optical fiber functions as a long path and extremely small volume gas cell. Firstly, the measurement sensitivity of the system is evaluated by using NO gas as a gas sample. The result shows that NO gas with 50 ppb concentration is measured by using a system with a laser-driven, high intensity light source and a 3-meter long, aluminum-coated hollow optical fiber. Then an absorption spectrum of breath sample is measured in the wavelength region of around 200-300 nm and from the spectrum, it is found that the main absorbing components in breath were H2O, isoprene, and O3 converted from O2 by radiation of ultraviolet light. Then the concentration of isoprene in breath is estimated by using multiple linear regression analysis.
Flexible polymer waveguides for light-activated therapy (Conference Presentation)
Moonseok Kim, Sheldon J. J. Kwok, Harvey H. Lin, et al.
Conventional light-activated therapies, such as photodynamic therapy (PDT), photochemical tissue bonding (PTB), collagen crosslinking (CXL), low-level light therapy (LLLT), and antimicrobial therapy utilize external light sources and light propagation through free space, limiting treatment to accessible and superficial areas of the body. Recent progress has been made in developing biocompatible polymer waveguides to enhance light delivery to deep tissues. To further expand clinical utility, waveguides should be flexible and tough enough to enable use in anatomically difficult-to-reach regions, while having the requisite optical properties to achieve uniform and efficient illumination of the target area. Here, we present a new class of flexible polymer waveguides optimized for uniform light extraction into tissues. Our slab waveguides comprise two designs: first, a flexible polydimethylsiloxane (PDMS) based elastomer for CXL, and second, a tough polyacrylamide and alginate hydrogel for large-area phototherapies. Our waveguides are optically transparent in the visible wavelengths (400-750 nm) and a multimode fiber is used to couple light into the waveguide. We characterized the light propagation through the waveguides and light extraction into tissue, and validated our results with optical simulation. By changing the thickness and scattering properties, uniform light extraction through the length of the waveguide could be achieved. We demonstrate proof-of-concept scleral photo-crosslinking of an ex vivo porcine eyeball for prevention of myopia.
Keynote
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Fiber lasers for medical diagnostics and treatments: state of the art, challenges and future perspectives
Fiber laser is a fast growing yet quite young type of laser with huge potential in healthcare due to versatility and reliability. The talk discusses present and future for fiber lasers for medical applications and address future challenges and competitions with other sources.
Optical Fibers and Sensors II
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Silica nanoparticle coated long-period grating for in situ monitoring of drug delivery thin films
Dielectric nanoparticle in integration with the long-period grating (LPG) is explored and its effect on the sensitivity is evaluated in the in situ monitoring of the deposition of drug delivery thin film. SiNPs were immobilized on the LPG via layer-by-layer self-assembly using poly allylamine hydrochloride (PAH). Theoretical calculation reveals that the SiNPs coating increases the evanescent field overlap in the surrounding of the LPG thus enhances its sensitivity. The increased total surface for the following thin film deposition also contributes to the enhancement of the sensitivity. Its unique capability for the in-situ monitoring of drug delivery thin film [chitosan (CHI) / Poly arylic acid (PAA) / Gentamicin sulfate (GS) /PAA]n through layer-by-layer assembly (LbL) was demonstrated with a sensitivity of 8.1 nm shift/tetralayer for LPG with 1 layer of SiNPs with 50 nm in diameter. The sensitivity enhancement of the LPG also depends heavily on the layer numbers and sizes of the SiNPs. The LPG with SiNPs of 8 layer numbers exhibits a sensitivity of only 1.2 nm shift/tetralayer. Control experiment of LPG without the SiNPs for the monitoring of [CHI/PAA/GS/PAA]n shows a sensitivity of 2.4 nm shift/tetralayer. This investigation suggests that SiNPs are effective in fine tune the optical property of the LPG. SiNPs coating thick enough can be used as an effective insulation for LPG from outer species. This investigation sets up the foundation for the development of SiNPs enabled optical fiber LPG sensor for the in-situ study of drug delivery LbL thin film.
On the customization of the irradiation patterns of probes for laser tumor ablation with integrated temperature sensing capabilities
Riccardo Gassino, Maria Azzena, Alberto Vallan, et al.
The paper reports some results on the customization of the irradiation pattern of an all-fiber applicator for laser induced thermal therapies of solid tumors. The probe exploits a double cladding fiber structure to simultaneously guide the high power beam for the ablation and the signals for the interrogation of embedded Bragg gratings that add temperature sensing capabilities. The probe was characterized using phantoms so as to mimic real situations while providing a repeatable environment for comparing the different solutions in terms of irradiation pattern shapes and induced temperature profiles.
Proton therapy dosimetry by using silica glass optical fiber microprobes
Arash Darafsheh, Reza Taleei, Alireza Kassaee, et al.
We investigated the feasibility of proton therapy dosimetry by using bare silica glass optical fibers. A silica glass fiber, with 400μm core diameter, was placed in proton radiation fields generated by a proton therapy cyclotron and simultaneously luminescence spectroscopy was performed to analyze the emission spectrum of the fiber tip. In order to measure the radiation absorbed dose at various depths in tissue-mimicking media, the fiber tip was embedded in a plastic slab and additional slabs of phantom were added sequentially. The spectrum of the irradiated fiber over the 400–700 nm sensitivity range of the spectrometer shows two distinct peaks at 460 and 650 nm, whose spectral shape is different from that of Čerenkov radiation. We found that the emission peak at 650 nm shows correlation with the radiation absorbed dose measured by a standard ion chamber device indicating the feasibility of proton dose measurement by using a bare silica fiber.
Optical Fibers and Sensors III
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Scintillating fiber optic dosimeters for breast and prostate brachytherapy
L. M. Moutinho, I. F. Castro, H. Freitas, et al.
Brachytherapy is a radiotherapy modality where the radioactive material is placed close to the tumor, being a common treatment for skin, breast, gynecological and prostate cancers. These treatments can be of low-dose-rate, using isotopes with mean energy of 30 keV, or high-dose-rate, using isotopes such as 192Ir with a mean energy of 380 keV. Currently these treatments are performed in most cases without in-vivo dosimetry for quality control and quality assurance.

We developed a dosimeter using small diameter probes that can be inserted into the patient's body using standard brachytherapy needles. By performing real-time dosimetry in breast and prostate brachytherapy it will be possible to perform real-time dose correction when deviations from the treatment plan are observed.

The dosimeter presented in this work was evaluated in-vitro. The studies consisted in the characterization of the dosimeter with 500 μm diameter sensitive probes (with a BCF-12 scintillating optical fiber) using an inhouse made gelatin breast phantom with a volume of 566 cm3. A breast brachytherapy treatment was simulated considering a tumor volume of 27 cm3 and a prescribed absolute dose of 5 Gy. The dose distribution was determined by the Inverse Planning Simulated Annealing (IPSA) optimization algorithm (ELEKTA).

The dwell times estimated from the experimental measurements are in agreement with the prescribed dwell times, with relative error below 3%. The measured signal-to-noise ratio (SNR) including the stem-effect contribution is below 3%.
SMART micro-scissors with dual motors and OCT sensors (Conference Presentation)
Chaebeom Yeo, Seonjin Jang, Hyun-cheol Park, et al.
Various end-effectors of microsurgical instruments have been developed and studied. Also, many approaches to stabilize the tool-tip using robotics have been studied such as the steady hand robot system, Micron, and SMART system. In our previous study, the horizontal SMART micro-scissors with a common path swept source OCT distance and one linear piezoelectric (PZT) motor was demonstrated as a microsurgical system. Because the outer needle is connected with a mechanical handle and moved to engage the tool tip manually, the tool tip position is instantaneously changed during the engaging. The undesirable motion can make unexpected tissue damages and low surgical accuracy. In this study, we suggest a prototype horizontal SMART micro-scissors which has dual OCT sensors and two motors to improve the tremor cancellation. Dual OCT sensors provide two distance information. Front OCT sensor detects a distance from the sample surface to the tool tip. Rear OCT sensors gives current PZT motor movement, acting like a motor encoder. The PZT motor can compensate the hand tremor with a feedback loop control. The manual engaging of tool tip in previous SMART system is replaced by electrical engaging using a squiggle motor. Compared with previous study, this study showed better performance in the hand tremor reduction. From the result, the SMART with automatic engaging may become increasingly valuable in microsurgical instruments.
Multiplexed fibre optic sensing in the distal lung (Conference Presentation)
Tushar R. Choudhary, Michael G. Tanner, Alicia Megia-Fernandez, et al.
We present a toolkit for a multiplexed pH and oxygen sensing probe in the distal lung using multicore fibres. Measuring physiological relevant parameters like pH and oxygen is of significant importance in understanding changes associated with disease pathology. We present here, a single multicore fibre based pH and oxygen sensing probe which can be used with a standard bronchoscope to perform in vivo measurements in the distal lung. The multiplexed probe consists of fluorescent pH sensors (fluorescein based) and oxygen sensors (Palladium porphyrin complex based) covalently bonded to silica microspheres (10 µm) loaded on the distal facet of a 19 core (10 µm core diameter) multicore fibre (total diameter of ~150 µm excluding coating). Pits are formed by selectively etching the cores using hydrofluoric acid, multiplexing is achieved through the self-location of individual probes on differing cores. This architecture can be expanded to include probes for further parameters. Robust measurements are demonstrated of self-referencing fluorophores, not limited by photobleaching, with short (100ms) measurement times at low (~10µW) illumination powers. We have performed on bench calibration and tests of in vitro tissue models and in an ovine whole lung model to validate our sensors. The pH sensor is demonstrated in the physiologically relevant range of pH 5 to pH 8.5 and with an accuracy of ± 0.05 pH units. The oxygen sensor is demonstrated in gas mixtures downwards from 20% oxygen and in liquid saturated with 20% oxygen mixtures (~8mg/L) down to full depletion (0mg/L) with ~0.5mg/L accuracy.
Interferometric and localized surface plasmon based fiber optic sensor
Harald Ian D. I. Muri, Andon Bano, Dag Roar Hjelme
We demonstrate a novel single point, multi-parameter, fiber optic sensor concept based on a combination of interferometric and plasmonic sensor modalities on an optical fiber end face. The sensor consists of a micro-Fabry-Perot interferometer in the form of a hemispherical stimuli-responsive hydrogel with immobilized gold nanoparticles. We present results of proof-of-concept experiments demonstrating local surface plasmon resonance (LSPR) sensing of refractive index (RI) in the visible range and interferometric measurements of volumetric changes of the pH stimuli-responsive hydrogel in near infrared range. The response of LSPR to RI (Δλr/ΔRI ∼ 877nm/RI) and the free spectral range (FSR) to pH (ΔpH/ΔFSR = 0.09624/nm) were measured with LSPR relatively constant for hydrogel swelling degree and FSR relatively constant for RI. We expect this novel sensor concept to be of great value for biosensors for medical applications.
Optical Fibers and Sensors IV
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Highly sensitive and selective biosensor based on graphene oxide coated long period grating
M. S. Shaikh, C. Liu, M. Partridge, et al.
We propose an optical fiber immunosensor based on graphene oxide coated dual-peak long period grating (GO-dLPG), in which GO-IgG linking layer is used for rapid immunoassays. The binding interaction between antibody and antigen produced a detectable optical signal in terms of grating resonant wavelength shift, which was proportional to the analyte concentration. By deposition of GO overlay, the bulk RI sensitivity of dLPG was enhanced around 150%. The GO-coated dLPG was biofunctionalized by the immobilization of IgG to generate the biosensor. The IgG-bound GO-dLPG was used to detect the anti-IgG and anti-PSA, respectively, demonstrating high sensitivity and selectivity. The GO-dLPG biosensor can be further developed as a biosensing platform with advantages of label-free, real-time and low limit of detection.
Fibre optic time-resolved spectroscopy using CMOS-SPAD arrays
K. Ehrlich, A. Kufcsák, N. Krstajić, et al.
In vivo fibre optic fluorescence-based sensing is the use of synthesised fluorophores which interrogate the local environment via variation in their fluorescence emission, addressed through an optic fibre. However, the emission intensity is influenced by intrinsic factors such as photobleaching, quantitative factors like concentration dependency and background signals from autofluorescence of tissue and the delivery optical fibre. Many of these problems can be addressed by using time-resolved spectroscopy which measures variations in the fluorescent lifetime. We present a versatile fibre-based time-resolved spectrograph based on a CMOS SPAD line sensor capable of acquiring time and spectral resolved fluorescent lifetime data in a single measurement exploiting the time-correlated single photon counting (TCSPC) technique. It is shown that these TCSPC histograms enable the differentiation between autofluorescence of tissue and synthesized fluorophores, as well as the removal of unwanted fibre background through post-processed time-gating. As a proof-of-principle application the pH- dependent changes in fluorescent lifetime of 5-carboxyuorescein (FAM) are measured.
Femtosecond laser fabrication of fiber based optofluidic platform for flow cytometry applications
Murat Serhatlioglu, Caglar Elbuken, Bulend Ortac, et al.
Miniaturized optofluidic platforms play an important role in bio-analysis, detection and diagnostic applications. The advantages of such miniaturized devices are extremely low sample requirement, low cost development and rapid analysis capabilities. Fused silica is advantageous for optofluidic systems due to properties such as being chemically inert, mechanically stable, and optically transparent to a wide spectrum of light. As a three dimensional manufacturing method, femtosecond laser scanning followed by chemical etching shows great potential to fabricate glass based optofluidic chips. In this study, we demonstrate fabrication of all-fiber based, optofluidic flow cytometer in fused silica glass by femtosecond laser machining. 3D particle focusing was achieved through a straightforward planar chip design with two separately fabricated fused silica glass slides thermally bonded together. Bioparticles in a fluid stream encounter with optical interrogation region specifically designed to allocate 405nm single mode fiber laser source and two multi-mode collection fibers for forward scattering (FSC) and side scattering (SSC) signals detection. Detected signal data collected with oscilloscope and post processed with MATLAB script file. We were able to count number of events over 4000events/sec, and achieve size distribution for 5.95μm monodisperse polystyrene beads using FSC and SSC signals. Our platform shows promise for optical and fluidic miniaturization of flow cytometry systems.
Analysis of anhydrous glucose and human serum assisted by Raman spectroscopy
Raman spectroscopy has been considered like a potentially important clinical tool for real-time diagnosis of disease and evaluation of living tissue, whit the proposal to development noninvasive glucose measurements in a near future, with lower power than other reported studies, in this work are reported experimental tests made with a excitation source of semiconductor laser of 785 nm and 35 mW power.

Measurements were made to different glucose concentrations, with variation from 50 mg/dL to 6000 mg/dL. For this, three intervals with different ranges of concentration were analyzed, these tests were put into plastic sampling cells, making incise the beam vertically on sample. In the same way measurements to serum human are reported, for healthy volunteers had 12 hours fasting and non-fasting conditions, with it's corresponding values of glucose taken through a conventional glucometer.

Freeze-dried human serum was poured on object-holder, in the case of human serum reconstitute, it was used container in which were previously kept samples. Nine spectra per test were obtained and subsequently average was calculated, the spectra were studied in a range of 500 to 1700 cm-1. This work explores the intensity variation of the bands of glucose in 1065 cm-1 and 1127 cm-1 as a function of glucose concentration. In the obtained results, there observes a behavior with positive slope in both substances, interrelation being observed between the measurements, being promissory for non-invasive measurement.
Optical Fibers and Sensors V
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Analysis of propagation properties of terahertz hollow-optical fiber by using time-domain spectroscopy and application for THz wave remote spectroscopy
K. Ito, T. Katagiri, Y. Matsuura
Terahertz pulse propagation in hollow optical fibers is investigated by using terahertz time-domain spectroscopy. From evaluation of transmission loss spectra of hollow optical fiber, it is found that TM11 mode propagates as well as TE11 mode that is the lowest order mode in terahertz metal-hollow fiber. Short-time Fourier transform is also applied for investigation of mode properties and as a result, it is confirmed that the interference peaks in the loss spectra are due to mode mixing in hollow optical fibers. Finally we performed a terahertz wave remote spectroscopy using the hollow optical fiber and acquired a clear transmission spectrum of the theophylline.
Microbend fiber optic sensor for perioperative pediatric vital signs monitoring
Zhihao Chen, Hwan Ing Hee, Soon Huat Ng, et al.
We have demonstrated a highly sensitive microbend fiber optic sensor for perioperative pediatric vital signs monitoring that is free from direct contact with skin, cableless, electromagnetic interference free and low cost. The feasibility of our device was studied on infants undergoing surgery and 10 participants ranging from one month to 12 months were enrolled. The sensor was placed under a barrier sheet on the operating table. All patients received standard intraoperative monitoring. The results showed good agreement in heart rate and respiratory rate between our device and the standard physiological monitoring when signals are clean.
Performance improvement of an all-optical Fabry Perot ultrasound detector
A highly sensitive Fiber-Optic Fabry Perot Ultrasound sensor with a self-written waveguide is presented in this work. A simulated device using Gold mirrors showed periodic resonance with Q-factor 1900 for 45 μm thick devices. Including a waveguide to limit lateral power losses resulted in improvement of Q-factor to 3200. Simulations also indicated greater improvement in Q-factor upon the introduction of waveguide with larger device thicknesses.

Subsequently, a prototype was fabricated on a single mode optical fiber. Benzocyclobutene was chosen as the cavity medium as it undergoes a refractive index change upon exposure to UV. The refractive index change in BCB upon UV exposure was studied using a phase grating. Upon confirming that 2-hour exposure produced a change of 0.004, a self-aligned waveguide was written into the cavity. A consequent increase in Q-factor from 2500 to 5200 was seen for an 80 μm thick device.

Simulation studies indicate further improvement when incorporating dielectric Bragg mirrors instead of Gold, with Q-factors of 6400 and 10200 with and without the waveguide. Therefore, the proposed design includes Dielectric Bragg mirrors as well as a self-aligned waveguide.

The fabrication techniques being fairly controlled and automated, this device is highly suitable for mass-manufacturing, making is possible to produce as an inexpensive, disposable device. A potential application is to integrate it within a commercial guidewire to create a smart guidewire capable of detecting vascular vessel walls in order to guide interventions for Chronic Total Occlusions, reducing risk of wall perforation, which is currently an unmet clinical need.
An inherently temperature insensitive fiber Bragg grating force sensor for in-vivo applications
John W. Arkwright, Luke Parkinson, Anthony Papageorgiou
We present a fiber Bragg grating sensor design that provides an inherently athermal response to a transverse applied load. The active element of the sensor is formed from two fibers helically wound around a common axis each containing an FBG element. The helical winding of the fibers is positioned within the transducer so that the FBG elements are coincident and located at the point where the axes of the fibers are in the orthogonal plane to the base of the sensor. An applied load acting on the sensor deflects the fibers sideways so that the upper FBG is compressed and the lower FBG is stretched causing a differential change in the Bragg wavelengths of each element. For small loads, the differential change in wavelength is linearly proportional to the applied force. A change in temperature causes identical change in Bragg wavelength on both FBG elements and therefore does not affect the differential change caused by the applied load. Using this design we have reduced the temperature dependence of our FBG sensors from ~13 pm per °C to a variation of less than 0.25 pm over a temperature range of 20 – 60 °C, with the residual temperature dependence being largely made up of temperature variations in the solid state spectrometer used to acquire data. These sensors are ideally suited for forming sensing arrays for monitoring in-vivo pressures and forces where fluctuations in temperature are unavoidable, and have been used successfully for monitoring the pressure induced beneath compression bandages.
Optical Fibers and Sensors VI
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Multi-spectral fiber spectroscopy in 0,4-16µm range for biomedical applications (Conference Presentation)
Viacheslav Artyushenko D.D.S.
Various biomedical applications of fiber optics in a broad spectral range 0,4-16μm span from endoscopic imaging and Photo Dynamic Diagnostics (PDD) to laser power delivery for minimal invasive laser surgery, tissue coagulation and welding, Photo Dynamic Therapy (PDT), etc. Present review will highlight the latest results in advanced fiber solutions for a precise tissue diagnostics and control of some therapy methods - for so called "theranostic".

Spectral fiber sensing for label free analysis of tissue composition helps to differentiate malignant and normal tissue to secure minimal invasive, but complete tumor removal or treatment. All key methods of Raman, fluorescence, diffuse reflection & MIR-absorption spectroscopy will be compared when used for the same spot of tissue - to select the most specific, sensitive and accurate method or to combine them for the synergy enhanced effect. The most informative spectral features for distinct organs/ tumor can be used to design special fiber sensors to be developed for portable and low cost applications with modern IT-features. Examples of multi-spectral tissue diagnostics promising for the future clinical applications will be presented to enable reduced mortality from cancer in the future. Translation of described methods into clinical practice will be discussed in comparison with the other method of optical diagnostics which should enhance modern medicine by less invasive, more precise and more effective methods of therapy to be fused with in-vivo diagnostics sensors & systems.
Chalcogenide glass sensors for bio-molecule detection
Pierre Lucas, Garrett J. Coleman, Christopher Cantoni, et al.
Chalcogenide glasses constitute the only class of materials that remain fully amorphous while exhibiting broad optical transparency over the full infrared region from 2-20 microns. As such, they can be shaped into complex optical elements while retaining a clear optical window that encompass the vibrational signals of virtually any molecules. Chalcogenide glasses are therefore ideal materials for designing biological and chemical sensors based on vibrational spectroscopy. In this paper we review the properties of these glasses and the corresponding design of optical elements for bio-chemical sensing. Amorphous chalcogenides offer a very wide compositional landscape that permit to tune their physical properties to match specific demands for the production of optical devices. This includes tailoring the infrared window over specific ranges of wavelength such as the long-wave infrared region to capture important vibrational signal including the “signature region” of micro-organisms or the bending mode of CO2 molecules. Additionally, compositional engineering enables tuning the viscosity-temperature dependence of the glass melt in order to control the rheological properties that are fundamental to the production of glass elements. Indeed, exquisite control of the viscosity is key to the fabrication process of many optical elements such as fiber drawing, lens molding, surface embossing or reflow of microresonators. Optimal control of these properties then enables the design and fabrication of optimized infrared sensors such as Fiber Evanescent Wave Spectroscopy (FEWS) sensors, Whispering Gallery Modes (WGM) micro-resonator sensors, nanostructured surfaces for integrated optics and surface-enhanced processes, or lens molding for focused collection of infrared signals. Many of these sensor designs can be adapted to collect and monitor the vibrational signal of live microorganisms to study their metabolism in controlled environmental conditions. Further materials engineering enable the design of opto-electrophoretic sensors that permit simultaneous capture and detection of hazardous bio-molecules such as bacteria, virus and proteins using a conducting glass that serves as both an electrode and an optical elements. Upon adequate spectral analysis such as Principal Component Analysis (PCA) or Partial Least Square (PLS) regression these devices enable highly selective identification of hazardous microorganism such as different strains of bacteria and food pathogens.
Optical Fibers and Sensors VII
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Performance characteristics of continuous multicore fiber optic sensor arrays
Tristan Kremp, Kenneth S. Feder, Wing Ko, et al.
We report on the optical and sensor performance characteristics of meter long continuous twisted multicore optical fiber gratings. We describe a method to analyze the optical performance of all the cores in the multicore array. We also report on the sensitivity of our arrays to local changes such as bend and twist. Our analysis provides guidance for the proper operating range of multicore fiber sensing arrays.
Fabrication of bundle-structured tube-leaky optical fibers for infrared thermal imaging
T. Kobayashi, T. Katagiri, Y. Matsuura
Bundled glass tubular fibers were fabricated by glass drawing technique for endoscopic infrared-thermal imaging. The bundle fibers were made of borosilicate glass and have a structure like a photonic crystal fiber having multiple hollow cores. Fabricated fibers have a length of 90 cm and each pixel sizes are less than 80 μm. By setting the thickness of glass wall to a quarter-wavelength optical thickness, light is confined in the air core as a leaky mode with a low loss owing to the interference effect of the thin glass wall and this type of hollow-core fibers is known as tube leaky fibers. The transmission losses of bundled fibers were firstly measured and it was found that bundled tube-leaky fibers have reasonably low transmission losses in spite of the small pixel size. Then thermal images were delivered by the bundled fibers combining with an InSb infrared camera. Considering applications with rigid endoscopes, an imaging system composed of a 30-cm long fiber bundle and a half-ball lens with a diameter of 2 mm was fabricated. By using this imaging system, a metal wire with a thickness of 200 μm was successfully observed and another test showed that the minimum detected temperature was 32.0 °C and the temperature resolution of the system was around 0.7 °C.
Optical Fibers and Sensors VIII
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Silver/polymer coated hollow glass waveguides for mid-IR transmission
Hollow glass waveguides (HGWs) have been successfully employed in surgical lasers, temperature and chemical sensors, and other applications requiring transmission of broadband, high-power infrared radiation. The design ofHGWsallows for fine-tuning of the optical response through the deposition of high-quality thin films within the hollowcore. One method of fabricatingHGWs for effective transmission in the infrared is to deposit a reflective metallic layer of silver, and then one or several dielectric layers on top of the silver layer. The addition of appropriate dielectric, or highly transmissive, layers to the HGW has shown to improve throughput and fibers can be modified to transmit optimally at particular wavelengths by altering the types of dielectrics used as well as their individual thicknesses. Increasingly, research in dielectric thin films for HGWs has gravitated towards polymers due to their inertness, ease of deposition, and thickness of film adjusted with concentration of solution instead of deposition kinetics. Poly (methyl methacrylate), polyethylene, and Chemours™ Teflon™ AF are three polymers previously untested as dielectric films in hollow waveguides in the mid-infrared. This work aims to assess the feasibility of these polymers as viable dielectric films in dichroic and multilayer thin-film stack waveguide applications. The three polymers were implemented as HGW dielectric thin films, and the resulting waveguides’ straight and bending losses were measured at CO2 (λ= 10.6 μm) and Er:YAG (λ= 2.94μm) laser wavelengths.
Improvement of transmission properties of visible pilot beam for polymer-coated silver hollow fibers with acrylic silicone resin as buffer layer for sturdy structure
Katsumasa Iwai, Hiroyuki Takaku, Mitsunobu Miyagi, et al.
Flexible hollow fibers with 530-μm-bore size were developed for infrared laser delivery. Sturdy hollow fibers were fabricated by liquid-phase coating techniques. A silica glass capillary is used as the substrate. Acrylic silicone resin is used as a buffer layer and the buffer layer is firstly coated on the inner surface of the capillary to protect the glass tube from chemical damages due to the following silver plating process. A silver layer was inner-plated by using the conventional silver mirror-plating technique. To improve adhesion of catalyst to the buffer layer, a surface conditioner has been introduced in the method of silver mirror-plating technique. We discuss improvement of transmission properties of sturdy polymer-coated silver hollow fibers for the Er:YAG laser and red pilot beam delivery.
Short- and long-term damage and annealing of improved UV-fibers using broadband UV light-source
Philipp Raithel, Arne Zimmer, Karl-Friedrich Klein, et al.
A new generation of multimode UV-fibers with reduced solarization defects featuring core diameters ranging from 70 to 600 μm diameter have been manufactured by optimizing fiber drawing and processing techniques. Generated by D2-lamp light, UV-induced losses at 214 nm saturation levels below 0.5 dB have been achieved for 2 m long samples after 4 hours. However, it was found that UV-induced loss is increasing slightly after 24 hours.

For applications in analytics or sensing, a plasma-based laser-driven light source has been introduced as an alternative to D2-lamps. However, the UV-defect concentration after 4 hours was found to be lower despite significantly higher spectral power density. Annealing effects due to VIS- and IR-light portion of the new lamp may have to be taken into account.

For the first time, we are concentrating on the short-term (< 20 min) effects of UV damaging in different UV-fibers due to different spectra; especially light power above 400 nm will be blocked or at least significantly reduced. In addition, the long-term behavior with both lamps and the effect on fiber core diameter is presented.
Development of a cylindrical diffusing optical fiber probe for pancreatic cancer therapy
Although the patients with cancer on pancreas or pancreaticobiliary duct have been increased, it is very difficult to detect and to treat the pancreatic cancer because of its low accessibility and obtuseness. The pancreatic cancer has been diagnosed using ultrasonography, blood test, CT, endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasonography (EUS) and etc. Normally, light can be delivered to the target by optical fibers through the ERCP or EUS. Diffusing optical fibers have been developed with various methods. However, many of them have mechanical and biological problems in the use of small-bend-radius apparatus or in tissue area. This study developed a therapeutic cylindrical diffusing optical fiber probe (CDOFP) for ERCP and EUS which has moderate flexibility and solidity to treat the cancer on pancreaticobiliary duct or pancreas. The CDOFP consists of a biocompatible Teflon tube and multimode glass fiber which has diffusing area processed with laser and high refractive index resin. The CDOFP was characterized to investigate the clinical feasibility and other applications of light therapy using diffusing optical fiber. The results presented that the CDOFP may be used in clinic by combining with endoscopic method, such as ERCP or EUS, to treat cancer on pancreas and pancreaticobiliary duct.
Poster Session
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Dual modal endoscopic cancer detection based on optical pH sensing and Raman spectroscopy
Soogeun Kim, ByungHyun Kim, Won Bum Sohn, et al.
To discriminate between normal and cancerous tissue, a dual modal approach using Raman spectroscopy and pH sensor was designed and applied. Raman spectroscopy has demonstrated the possibility of using as diagnostic method for the early detection of precancerous and cancerous lesions in vivo. It also can be used in identifying markers associated with malignant change. However, Raman spectroscopy lacks sufficient sensitivity due to very weak Raman scattering signal or less distinctive spectral pattern. A dual modal approach could be one of the solutions to solve this issue. The level of extracellular pH in cancer tissue is lower than that in normal tissue due to increased lactic acid production, decreased interstitial fluid buffering and decreased perfusion. High sensitivity and specificity required for accurate cancer diagnosis could be achieved by combining the chemical information from Raman spectrum with metabolic information from pH level. Raman spectra were acquired by using a fiber optic Raman probe, a cooled CCD camera connected to a spectrograph and 785 nm laser source. Different transmission spectra depending on tissue pH were measured by a lossy-mode resonance sensor based on fiber optic. The discriminative capability of pH-Raman dual modal method was evaluated using principal component analysis (PCA). The obtained results showed that the pH-Raman dual modal approach can improve discriminative capability between normal and cancerous tissue, which can lead to very high sensitivity and specificity. The proposed method for cancer detection is expected to be used in endoscopic diagnosis later.
Investigation into surface interaction between the contact lens, the upper eyelid and cornea using optical coherence tomography
R. Morecroft, M. J. Carré, R. Lewis, et al.
Background and Aim: Over 50% of the total 125 million contact lens users complain of discomforts due to contact lenses. The aim of the project is to understand the effect of contact lenses on the morphological parameters of cornea and eyelid surfaces.

Methods and results: Five volunteers were recruited for this study (3 soft contact lens users and 2 non-users). The volunteers were imaged using a slit lamp and Optical Coherence Tomography (OCT) before and after a period of 6-7 hours. There was a significant increase in epidermal thickness of the eyelid for contact lens users compared to non-users. In addition, the upper eyelid roughness for contact lens users and non-users increased significantly. This might be due to deposition of particles from the eyelid during the wiping process.

Conclusions: Contact lens usage does affect the morphological parameters of eyelid. OCT is a powerful tool to measure these morphological changes in the eye. However, more volunteers must be recruited to get a better understanding of these changes.
Cell counting system by using single fiber interferometer
Seung Seok Lee, Joo Ha Kim, Eun Seo Choi
We proposed a cell-counting method using optical fiber interferometer and demonstrated the performance of the proposed method. The cell counting means the counting or the quantification of individual cells. Its application ranges from the biological research to practical disease diagnosis. As a conventional approach for cell counting, various methods are employed. Among them, flow cytometry is quite accurate and exact method but it uses bulk and expensive optical equipment. When image-based methods are exploited, the limited field of view obtained by microscope is considered for cell counting. From this reason, problem of time consuming for whole cell counting is to be solved. The proposed method utilized single-mode optical fiber and high-speed spectrometer. Light beam having broad spectral bandwidth over 100 nm at 850-nm central wavelength is irradiated to a flow channel through fiber from top to bottom. Different optical path length differences are made whether the cell is passing though the flow channel across the beam area or not. The difference of optical path lengths in the beam area due to the cell induces interference signal depending on optical thickness of the cell. By measuring a series of interferences, the number of cells can be analyzed. The proposed system can be implemented without any expensive and perform the cell counting in the absence of complex image analysis. Interferometer-based cell counting can be a good alternative to the reported cell-counting methods.