1,720,975 research outputs found
Fiber bragg gratings for temperature measurements under thermal gradients. Comparison between two different lengths
Full text linkIn recent decades, Fiber Bragg grating sensors (FBGs) found widespread acceptance in several biomedical applications thanks to their indisputable advantages.
thermal ablation treatments (TATs) account for one of the fields where FBGs have gained large applicability for temperature measurements. The sensing element
ength can affect the accuracy of the FBG measurement in this application. A longer length provides a more prominent peak in the FBG reflected spectrum, resulting
o n a higher signal-to-noise ratio (SNR). A shorter FBG length implies a lower SNR but offers the benefits of better spatial resolution. Therefore, the choice of an
adequate length can be crucial to minimize measurement errors, but the literature lacks exhaustive investigations on this parameter. The aim of our study is to
supply additional knowledge about the effect of two different FBG lengths on temperature estimation in the presence of linear thermal gradients and with gradients mimicking the condition caused by TATs. In both cases, we compared the output of a 10 mm FBG with those of four FBGs 1 mm long, using a thermal camera as a reference instrument. Results suggest the better suitability of shorter sensors to retrieve thermal gradient information along their position instead of the longer FBG, which could lead to unacceptable measurement errors during TATs
Investigating FBG Sensor Arrangements and Computational Modeling in Photothermal Laser Treatment
No full textA review on radiofrequency, laser, and microwave ablations and their thermal monitoring through fiber Bragg gratings
No full text: Thermal ablation of tumors aims to apply extreme temperatures inside the target tissue to achieve substantial tumor destruction in a minimally invasive manner. Several techniques are comprised, classified according to the type of energy source. However, the lack of treatment selectivity still needs to be addressed, potentially causing two risks: i) incomplete tumor destruction and recurrence, or conversely, ii) damage of the surrounding healthy tissue. Therefore, the research herein reviewed seeks to develop sensing systems based on fiber Bragg gratings (FBGs) for thermal monitoring inside the lesion during radiofrequency, laser, and microwave ablation. This review shows that, mainly thanks to multiplexing and minimal invasiveness, FBGs provide an optimal sensing solution. Their temperature measurements are the feedback to control the ablation process and allow to investigate different treatments, compare their outcomes, and quantify the impact of factors such as proximity to thermal probe and blood vessels, perfusion, and tissue type
Fiber Bragg Grating Probe for Relative Humidity and Respiratory Frequency Estimation: Assessment during Mechanical Ventilation
No full textFiber Bragg grating (FBG) sensors have gained popularity in medicine for some valuable features, such as small size, immunity to electromagnetic interferences, and good metrological properties. Among several applications, this technology has been used in the analysis of gases in mechanical ventilation. In this field, in particular during invasive ventilation, the gas delivered by the ventilator must be warmed and humidified in order to reach the patients with optimal conditions (100% of relative humidity and 37 °C). The most popular device used to accomplish this task is the heated wire humidifiers (HWHs). Unfortunately, their performances are influenced by ventilatory settings (e.g., respiratory frequency) and environmental conditions. The aim of this paper is to fabricate a probe based on an FBG sensor able to monitor both the gas relative humidity and the respiratory frequency. This information can be used as a feedback to improve the performance of the HWHs. The probe consists of a needle, which houses an FBG sensor coated by hygroscopic material (i.e., agar). This solution allows an easy insertion of the probe within the ducts connecting the ventilator to the patient. The proposed system has been assessed during mechanical ventilation at different respiratory frequencies. Future testing will be focused on the development of a system able to monitor other parameters that influence the HWHs performances (e.g., gas temperature and minute volume)
Wearable 3D-Printed Thumb-Shaped Device Based on Fiber Bragg Grating Sensor for Epidural Space Detection
Full text linkFiber Bragg grating sensors (FBGs) are increasingly popular in various biomedical fields due to their undeniable benefits, hardly found in other sensing technologies. To overcome FBGs' inherent fragility, encapsulation in other hosting materials, such as silicone rubber or resins, has been widely practiced. This approach allowed for high flexibility and adaptability of the developed devices but can be time-consuming and labor-intensive. Fused deposition modeling (FDM) has recently been proposed to develop 3D-printed devices embedding FBGs, enabling the deployment of systems with high repeatability, accuracy, and fast fabrication time. The exploitation of 3D-printed device based on FBG for biomedical applications is still little explored in the literature. In this article, we proposed an application never yet investigated to assist physicians in performing epidural procedures. Accurately detecting the epidural space (ES) in these treatments is highly challenging as it relies on the clinician's perception. Moreover, due to ES small size, the risk of failure is common in clinical practice. In this field, state-of-the-art solutions have been devised to instrument the generally used needle or the syringe plunger. These solutions can obstruct the drug delivery inside the needle or contaminate the sterile field. In this study, we propose a 3D-printed thumb-shaped device embedding a single FBG conceived to be worn under a clinician's glove, thus overcoming the limitations associated with the existing systems. Design, fabrication, and metrological characterization of the proposed system are reported. Furthermore, a feasibility assessment in a real clinical scenario demonstrated its ability to detect the ES correctly
FBG-Based Mattress for Heart Rate Monitoring in Different Breathing Conditions
Full text linkIn recent years, extensive investigations have been geared toward finding unobtrusive solutions for monitoring cardiorespiratory activity as an alternative to traditional clinical methods. Among others, the ones based on fiber Bragg grating (FBG) sensors reveal remarkable promise for monitoring respiratory rate (RR) and heart rate (HR). The present study investigates the performance of a mattress based on a 13-FBG array for HR continuous estimation. First, a metrological characterization was performed to assess system characteristics under frequencies simulating typical HR values [i.e., 60, 90, and 120 beats per minute (bpm)]. Then, the proposed device was tested on eight healthy volunteers (both males and females) in the presence of different breathing stages (i.e., quiet breathing and tachypnea) while mimicking common sleeping postures (i.e., supine, left side, and prone). The assessment of HR measurements under different breathing regimes and postures has rarely been addressed in FBG-based technologies. The achieved results suggest that the proposed mattress has promising capability in reliably estimating HR values. These results together with the ones obtained in terms of RR monitoring in a recent study reveal the high potential for monitoring cardiorespiratory activity
Assessment of a Multi-Sensor FBG-Based Wearable System in Sitting Postures Recognition and Respiratory Rate Evaluation of Office Workers
No full text: Due to prolonged incorrect sitting posture, upper body musculoskeletal disorders (UBMDs) are largely widespread among sedentary workers. Monitoring employees' sitting behaviors could be of great help in minimizing UBMDs' occurrence. In addition, being primarily influenced by psycho-physical stress conditions, respiratory rate (RR) would be a further useful parameter to delineate the workers' state of health. Wearable systems have emerged as a viable option for sitting posture and RR monitoring since enable continuous data collecting with no posture disturbances. Nevertheless, the main limits are poor fit, cumbersomeness, and movement restriction resulting in discomfort for the user. In addition, only few wearable solutions can track both these parameters contextually. To address these problems, in this study a flexible wearable system composed of seven modular sensing elements based on fiber Bragg grating (FBG) technology and designed to be worn on the back has been proposed to recognize the most common sitting postures (i.e., kyphotic, upright and lordotic) and estimate RR. The assessment was performed on ten volunteers showing good performances in postures recognition via Naïve Bayes classificator (accuracy >96.9%) and agreement with the benchmark in RR estimation (MAPE ranging between 0.74% and 3.83%, MODs close to zero, and LOAs between 0.76 bpm and 3.63 bpm). The method was then successfully tested on three additional subjects under different breathing conditions. The wearable system could offer great support for a better understanding of the workers' posture attitudes and contribute to gathering RR information to depict an overall picture of the users' state of health
Gold nanoparticles mediation and fiber optics thermal monitoring for enhanced laser ablation
No full textGoing 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
- …
