1,721,073 research outputs found
Fiber-optic sensors for biomedical applications
No full textThis authoritative new resource presents fiber optic sensors and their applications in medical device design and biomedical engineering. Readers gain an understanding of which technology to use and adopt, and how to connect technologies with their respective applications. This book explores the innovation of diagnostics and how to use diagnostic tools.
Principles of fiber optic sensing are covered and include details about intensity-based sensors, fiber bragg gratings, distributed sensors, and fabry-perot interferometers. This book explores interrogation software, standards for medical sensors, and discusses protocols and tools for validation. Various medical device engineering and applications are examined, including sensor catheterization, cardiovascular sensors, diagnostic in gastroscopy, urology, neurology, sensing in thermal ablation. Applications and detection of SPR sensors are presented, along with minimally invasive robotic surgery, smart textiles, wearable sensors and fiber-optic spectrometric sensors. This is a one-stop reference on fiber optic sensors for biomed applications
Fiber-Optic Temperature and Pressure Sensors Applied to Radiofrequency Thermal Ablation in Liver Phantom: Methodology and Experimental Measurements
Full text linkRadiofrequency thermal ablation (RFA) is a procedure aimed at interventional cancer care and is applied to the treatment of small- and midsize tumors in lung, kidney, liver, and other tissues. RFA generates a selective high-temperature field in the tissue; temperature values and their persistency are directly related to themortality rate of tumor cells. Temperature measurement in up to 3–5 points, using electrical thermocouples, belongs to the present clinical practice of RFA and is the foundation of a physical model of the ablation process. Fiber-optic sensors allow extending the detection of biophysical parameters to a vast plurality of sensing points, using miniature and noninvasive technologies that do not alter the RFA pattern.This work addresses the methodology for
optical measurement of temperature distribution and pressure using four different fiber-optic technologies: fiber Bragg gratings (FBGs), linearly chirped FBGs (LCFBGs),Rayleigh scattering-based distributed temperature system (DTS), and extrinsic Fabry-Perot interferometry (EFPI). For each instrument, methodology for ex vivo sensing, as well as experimental results, is reported, leading to the application of fiber-optic technologies in vivo.The possibility of using a fiber-optic sensor network, in conjunction with a suitable ablation device, can enable smart ablation procedure whereas ablation parameters are dynamically changed
Performance analysis of peak tracking techniques for fiber Bragg grating interrogation systems
Full text linkIn this paper, we propose a spectral correlation-based technique for tracking the wavelength shift of a fiber Bragg grating. We compared this approach, by means of a Monte Carlo numerical simulation, to the typical peak tracking techniques applied in classic interrogation systems. As result, we obtained a considerable gain in terms of noise tolerance (about 20 dB), which can be further incremented by selecting large-bandwidth gratings.
This permits to increase the power budget of a fiber Bragg grating interrogator without changing the optical layout, overcoming classical limitations of commercial and custom systems. Penalties due to the non-idealities have been evaluated through the same Monte Carlo approach. Finally, we discuss a practical application of the peak tracking techniques to a fiber Bragg grating-based weight sensor, in which we applied the spectral correlation to track both the Bragg wavelength position, spectral deformations due to high strain, and spectral non-linearity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Weigh-in-motion through fibre Bragg grating optical sensors
No full textA fast, high-resolution fibre Bragg grating sensing system for weigh-in- motion applications is presented. The interrogator uses standard telecom photonic components and employs signal processing to improve the accuracy down to 1 micro-epsilon. The system has been applied to a speed bump, achieving an excellent reproduction of the bump structural deformation
Analysis and Design of Chirped Fiber Bragg Grating for Temperature Sensing for Possible Biomedical Applications
No full textIn this paper, we present the design and analysis of chirped fiber Bragg grating (CFBG) sensors, optimized for temperature measurements. The transfer matrix method has been used to simulate the CFBGs and to study their thermal response. The simulations have been carried out with different temperature profiles in order to understand how the CFBG thermal response varies as a function of the grating design parameters and, thus, to optimize the design for the specific application. Finally, to assess the numerical simulations, a series of experimental tests was performed showing very good agreement
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