48 results found
Gao A, Liu N, Shen M, et al., 2020, Laser-profiled continuum robot with integrated tension sensing for simultaneous shape and tip force estimation, Soft Robotics, Vol: 7, Pages: 421-443, ISSN: 2169-5172
The development of miniaturized continuum robots has a wide range of applications in minimally invasive endoluminal interventions. To navigate inside tortuous lumens without impinging on the vessel wall and causing tissue damage or the risk of perforation, it is necessary to have simultaneous shape sensing of the continuum robot and its tip contact force sensing with the surrounding environment. Miniaturization and size constraint of the device have precluded the use of conventional sensing hardware and embodiment schemes. In this study, we propose the use of optical fibers for both actuation and tension/shape/force sensing. It uses a model-based method with structural compensation, allowing direct measurement of the cable tension near the base of the manipulator without increasing the dimensions. It further structurally filters out disturbances from the flexible shaft. In addition, a model is built by considering segment differences, cable interactions/cross talks, and external forces. The proposed model-based method can simultaneously estimate the shape of the manipulator and external force applied onto the robot tip. Detailed modeling and validation results demonstrate the accuracy and reliability of the proposed method for the miniaturized continuum robot for endoluminal intervention.
Keshavarz M, Wales DJ, Seichepine F, et al., 2020, Induced neural stem cell differentiation on a drawn fiber scaffold-toward peripheral nerve regeneration, Biomedical Materials, Vol: 15, ISSN: 1748-6041
To achieve regeneration of long sections of damaged nerves, restoration methods such as direct suturing or autologous grafting can be inefficient. Solutions involving biohybrid implants, where neural stem cells are grown in vitro on an active support before implantation, have attracted attention. Using such an approach, combined with recent advancements in microfabrication technology, the chemical and physical environment of cells can be tailored in order to control their behaviors. Herein, a neural stem cell polycarbonate fiber scaffold, fabricated by 3D printing and thermal drawing, is presented. The combined effect of surface microstructure and chemical functionalization using poly-ʟ-ornithine (PLO) and double-walled carbon nanotubes (DWCNTs) on the biocompatibility of the scaffold, induced differentiation of the neural stem cells (NSCs) and channeling of the neural cells was investigated. Upon treatment of the fiber scaffold with a suspension of DWCNTs in PLO (0.039 gL-1) and without recombinants a high degree of differentiation of NSCs into neuronal cells was confirmed by using nestin, galactocerebroside (GalC) and doublecortin (Dcx) immunoassays. These findings illuminate the potential use of this biohybrid approach for the realization of future nerve regenerative implants.
Many motion-active materials have recently emerged, with new methods of integration into actuator components and systems-on-chip. Along with established microprocessors, interconnectivity capabilities and emerging powering methods, they offer a unique opportunity for the development of interactive millimeter and micrometer scale systems with combined sensing and actuating capabilities. The amplification of nanoscale material motion to a functional range is a key requirement for motion interaction and practical applications, including medical micro-robotics, micro-vehicles and micro-motion energy harvesting. Motion amplification concepts include various types of leverage, flextensional mechanisms, unimorphs, micro-walking /micro-motor systems, and structural resonance. A review of the research state-of-art and product availability shows that the available mechanisms offer a motion gain in the range of 10. The limiting factor is the aspect ratio of the moving structure that is achievable in the microscale. Flexures offer high gains because they allow the application of input displacement in the close vicinity of an effective pivotal point. They also involve simple and monolithic fabrication methods allowing combination of multiple amplification stages. Currently, commercially available motion amplifiers can provide strokes as high as 2% of their size. The combination of high-force piezoelectric stacks or unimorph beams with compliant structure optimization methods is expected to make available a new class of high-performance motion translators for microsystems.
Cameron SJS, Bodai Z, Temelkuran B, et al., 2019, Utilisation of Ambient Laser Desorption Ionisation Mass Spectrometry (ALDI-MS) improves lipid-based microbial species level identification, Scientific Reports, Vol: 9, ISSN: 2045-2322
The accurate and timely identification of the causative organism of infection is important in ensuring the optimum treatment regimen is prescribed for a patient. Rapid evaporative ionisation mass spectrometry (REIMS), using electrical diathermy for the thermal disruption of a sample, has been shown to provide fast and accurate identification of microorganisms directly from culture. However, this method requires contact to be made between the REIMS probe and microbial biomass; resulting in the necessity to clean or replace the probes between analyses. Here, optimisation and utilisation of ambient laser desorption ionisation (ALDI) for improved speciation accuracy and analytical throughput is shown. Optimisation was completed on 15 isolates of Escherichia coli, showing 5 W in pulsatile mode produced the highest signal-to-noise ratio. These parameters were used in the analysis of 150 clinical isolates from ten microbial species, resulting in a speciation accuracy of 99.4% - higher than all previously reported REIMS modalities. Comparison of spectral data showed high levels of similarity between previously published electrical diathermy REIMS data. ALDI does not require contact to be made with the sample during analysis, meaning analytical throughput can be substantially improved, and further, increases the range of sample types which can be analysed in potential direct-from-sample pathogen detection.
Giataganas P, Hughes M, Payne C, et al., 2019, Intraoperative robotic-assisted large-area high-speed microscopic imaging and intervention, IEEE Transactions on Biomedical Engineering, Vol: 66, Pages: 208-216, ISSN: 0018-9294
IEEE Objective: Probe-based confocal endomicroscopy is an emerging high-magnification optical imaging technique that provides in-vivo and in-situ cellular-level imaging for real-time assessment of tissue pathology. Endomicroscopy could potentially be used for intraoperative surgical guidance, but it is challenging to assess a surgical site using individual microscopic images due to the limited field-of-view and difficulties associated with manually manipulating the probe. Methods: In this paper, a novel robotic device for large-area endomicroscopy imaging is proposed, demonstrating a rapid, but highly accurate, scanning mechanism with image-based motion control which is able to generate histology-like endomicroscopy mosaics. The device also includes, for the first time in robotic-assisted endomicroscopy, the capability to ablate tissue without the need for an additional tool. Results: The device achieves pre-programmed trajectories with positioning accuracy of less than 30um, the image-based approach demonstrated that it can suppress random motion disturbances up to 1.25mm/s. Mosaics are presented from a range of ex-vivo human and animal tissues, over areas of more than 3mm<formula><tex>$^2$</tex></formula>, scanned in approximate 10s. Conclusion: This work demonstrates the potential of the proposed instrument to generate large-area, high-resolution microscopic images for intraoperative tissue identification and margin assessment. Significance: This approach presents an important alternative to current histology techniques, significantly reducing the tissue assessment time, while simultaneously providing the capability to mark and ablate suspicious areas intraoperatively.
Karaman M, Gun T, Temelkuran B, et al., 2017, Comparison of fiber delivered CO2 laser and electrocautery in transoral robot assisted tongue base surgery, European Archives of Oto-Rhino-Laryngology, Vol: 274, Pages: 2273-2279, ISSN: 0937-4477
To compare intra-operative and post-operative effectiveness of fiber delivered CO2 laser to monopolar electrocautery in robot assisted tongue base surgery. Prospective non-randomized clinical study. Twenty moderate to severe obstructive sleep apnea (OSA) patients, non-compliant with Continuous Positive Airway Pressure (CPAP), underwent Transoral Robotic Surgery (TORS) using the Da Vinci surgical robot in our University Hospital. OSA was treated with monopolar electrocautery in 10 patients, and with flexible CO2 laser fiber in another 10 patients. The following parameters in the two sets are analyzed: Intraoperative bleeding that required cauterization, robot operating time, need for tracheotomy, postoperative self-limiting bleeding, length of hospitalization, duration until start of oral intake, pre-operative and post-operative minimum arterial oxygen saturation, pre-operative and post-operative Epworth Sleepiness Scale score, postoperative airway complication and postoperative pain. Mean follow-up was 12 months. None of the patients required tracheotomy and there were no intraoperative complications related to the use of the robot or the CO2 laser. The use of CO2 laser in TORS-assisted tongue base surgery resulted in less intraoperative bleeding that required cauterization, shorter robot operating time, shorter length of hospitalization, shorter duration until start of oral intake and less postoperative pain, when compared to electrocautery. Postoperative apnea–hypopnea index scores showed better efficacy of CO2 laser than electrocautery. Comparison of postoperative airway complication rates and Epworth sleepiness scale scores were found to be statistically insignificant between the two groups. The use of CO2 laser in robot assisted tongue base surgery has various intraoperative and post-operative advantages when compared to monopolar electrocautery.
Feller-Kopman D, Lukanich JM, Shapira G, et al., 2008, Gas flow during Bronchoscopic ablation therapy causes gas emboli to the heart, CHEST, Vol: 133, Pages: 892-896, ISSN: 0012-3692
This chapter discusses the properties, applications, and manufacture of hollow-core fibers. Hollow-core fibers guide light by means of a reflective cladding. Because the index of refraction of the hollow core is smaller than that of the cladding materials, the guiding mechanism cannot be based on total internal reflection, as is the case for traditional optical fibers. Instead, three major types of reflective cladding are used-a metal tube with optional dielectric coating, a multilayer dielectric Bragg mirror, or a two-dimensional photonic crystal. The simplest method for guiding light in a hollow core is by enclosing the core with a highly reflective metal. The metal acts as a mirror, so that fields from the core incident on the metal are reflected back into the core, providing the confinement mechanism. When the interior of the waveguide consists of a single homogeneous dielectric material, the mode fields can be separated into two polarizations-transverse electric and transverse magnetic with vanishing axial components of the electric and magnetic fields, respectively. © 2007 Elsevier Inc. All rights reserved.
Feller-Kopman DJ, Shapira G, Schori B, et al., 2007, Detection of gas emboli in bronchoscopic ablation therapy performed under zero flow and low flow conditions: A qualitative comparative animal study, CHEST 2007 Conference, Publisher: AMER COLL CHEST PHYSICIANS, Pages: 425S-425S, ISSN: 0012-3692
Abouraddy AF, Bayindir M, Benoit G, et al., 2007, Towards multimaterial multifunctional fibres that see, hear, sense and communicate, NATURE MATERIALS, Vol: 6, Pages: 336-347, ISSN: 1476-1122
Mizaikoff B, Young C, Charlton C, et al., 2006, Trace Sensing with Miniaturized Mid-Infrared Sensors, 5th IEEE Sensors Conference, Publisher: IEEE, Pages: 331-+, ISSN: 1930-0395
Skorobogatiy A, Jacobs SA, Johnson SG, et al., 2005, Heating of hollow photonic Bragg fibers from field propagation, coupling, and bending, JOURNAL OF LIGHTWAVE TECHNOLOGY, Vol: 23, Pages: 3517-3525, ISSN: 0733-8724
Charlton C, Temelkuran B, Dellemann G, et al., 2005, Midinfrared sensors meet nanotechnology: Trace gas sensing with quantum cascade lasers inside photonic band-gap hollow waveguides, APPLIED PHYSICS LETTERS, Vol: 86, ISSN: 0003-6951
Torres D, Weisberg O, Shapira G, et al., 2005, OmniGuide photonic bandgap fibers for flexible delivery of CO2 laser energy for laryngeal and airway surgery, Conference on Photonic Therapeutics and Diagnostics, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, Pages: 310-321, ISSN: 0277-786X
Benoit G, Hart SD, Temelkuran B, et al., 2003, Static and dynamic properties of optical microcavities in photonic bandgap yarns, ADVANCED MATERIALS, Vol: 15, Pages: 2053-+, ISSN: 0935-9648
Ozbay E, Temelkuran B, Bayindir M, 2003, Microwave applications of photonic crystals, Progress in Electromagnetics Research, Vol: 41, Pages: 185-209, ISSN: 1070-4698
We have demonstrated guiding and bending of electromagnetic (EM) waves in planar and coupled-cavity waveguides built around three-dimensional layer-by-layer photonic crystals. We observed full transmission of the EM waves through these waveguide structures. The dispersion relations obtained from the experiments were in good agreement with the predictions of our waveguide models. We also reported a resonant cavity enhanced (RCE) effect by placing microwave detectors in defect structures. A power enhancement factor of 3450 was measured for planar cavity structures. Similar defects were used to achieve highly directional patterns from monopole antennas.
Temelkuran B, Hart SD, Benoit G, et al., 2002, Wavelength-scalable hollow optical fibres with large photonic bandgaps for CO2 laser transmission, NATURE, Vol: 420, Pages: 650-653, ISSN: 0028-0836
Hart SD, Maskaly GR, Temelkuran B, et al., 2002, External reflection from omnidirectional dielectric mirror fibers, SCIENCE, Vol: 296, Pages: 510-513, ISSN: 0036-8075
Biswas R, Ozbay E, Temelkuran B, et al., 2001, Exceptionally directional sources with photonic-bandgap crystals, JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, Vol: 18, Pages: 1684-1689, ISSN: 0740-3224
Temelkuran B, Thomas EL, Joannopoulos JD, et al., 2001, Low-loss infrared dielectric material system for broadband dual-range omnidirectional reflectivity, OPTICS LETTERS, Vol: 26, Pages: 1370-1372, ISSN: 0146-9592
Ergun AS, Temelkuran B, Ozbay E, et al., 2001, A new detection method for capacitive micromachined ultrasonic transducers, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 48, Pages: 932-942, ISSN: 0885-3010
Bayindir M, Ozbay E, Temelkuran B, et al., 2001, Guiding, bending, and splitting of electromagnetic waves in highly confined photonic crystal waveguides, PHYSICAL REVIEW B, Vol: 63, ISSN: 2469-9950
Temelkuran B, Bayindir M, Ozbay E, et al., 2001, Quasimetallic silicon micromachined photonic crystals, APPLIED PHYSICS LETTERS, Vol: 78, Pages: 264-266, ISSN: 0003-6951
Bayindir M, Ozbay E, Temelkuran B, et al., 2001, Experimental demonstration of highly confined photonic crystal based waveguides
Ozbay E, Temelkuran B, Bayindir M, 2001, Physics and applications of photonic crystals, Conference of the NATO Advanced-Study-Institute on Photonic Crystals and Light Localization, Publisher: SPRINGER, Pages: 279-303, ISSN: 1568-2609
Biswas R, Ozbay E, Temelkuran B, et al., 2001, Applications of photonic crystals to directional antennas, Conference of the NATO Advanced-Study-Institute on Photonic Crystals and Light Localization, Publisher: SPRINGER, Pages: 321-328, ISSN: 1568-2609
Bayindir M, Ozbay E, Temelkuran B, et al., 2001, Experimental demonstration of highly confined photonic crystal based waveguides
© 2001 Optical Soc. Of America. Summary form only given. There is great deal of interest in developing photonic crystal based waveguides where one can confine and efficiently guide the light around sharp corners. Guiding the light without losses, and even through sharp corners was observed in two-dimensional (2D) photonic crystals. However, to avoid the leakage problem in 2D structures, either one has to extend the size of the photonic crystal in the vertical direction, or use a strong index-guiding mechanism in the vertical direction. A way to eliminate the leakage is to use a three-dimensional (3D) photonic crystal. Here, we demonstrate the guiding and bending of EM waves in highly confined waveguides which were constructed by removing a single rod from a perfect 3D layer-by-layer photonic crystal.
Bayindir M, Temelkuran B, Ozbay E, 2000, Photonic-crystal-based beam splitters, APPLIED PHYSICS LETTERS, Vol: 77, Pages: 3902-3904, ISSN: 0003-6951
Bayindir M, Temelkuran B, Ozbay E, 2000, Guiding and bending of photons via hopping in three-dimensional photonic crystals, Conference on Quantum Electronics and Laser Science (QELS) - Technical Digest Series, Pages: 95-96
A new mechanism to manipulate the propagation of electromagnetic waves in 3D photonic crystals is proposed and demonstrated. Photons hop from one evanescent defect mode to the next one regardless of the direction of propagation. A complete (near 100%) transmission along a straight path and around sharp corners were observed experimentally. The measured dispersion relation of the waveguiding band agrees well with the results of the classical wave analog of tight-binding method.
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