| 1. |
- Asan, Noor Badariah, 1984-, et al.
(författare)
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Assessment of Blood Vessel Effect on Fat-Intrabody Communication Using Numerical and Ex-Vivo Models at 2.45 GHZ
- 2019
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Ingår i: IEEE Access. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2169-3536. ; 7, s. 89886-89900
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Tidskriftsartikel (refereegranskat)abstract
- The potential offered by the intra-body communication (IBC) over the past few years has resulted in a spike of interest for the topic, specifically for medical applications. Fat-IBC is subsequently a novel alternative technique that utilizes fat tissue as a communication channel. This work aimed to identify such transmission medium and its performance in varying blood-vessel systems at 2.45 GHz, particularly in the context of the IBC and medical applications. It incorporated three-dimensional (3D) electromagnetic simulations and laboratory investigations that implemented models of blood vessels of varying orientations, sizes, and positions. Such investigations were undertaken by using ex-vivo porcine tissues and three blood-vessel system configurations. These configurations represent extreme cases of real-life scenarios that sufficiently elucidated their principal influence on the transmission. The blood-vessel models consisted of ex-vivo muscle tissues and copper rods. The results showed that the blood vessels crossing the channel vertically contributed to 5.1 dB and 17.1 dB signal losses for muscle and copper rods, respectively, which is the worst-case scenario in the context of fat-channel with perturbance. In contrast, blood vessels aligned-longitudinally in the channel have less effect and yielded 4.5 dB and 4.2 dB signal losses for muscle and copper rods, respectively. Meanwhile, the blood vessels crossing the channel horizontally displayed 3.4 dB and 1.9 dB signal losses for muscle and copper rods, respectively, which were the smallest losses among the configurations. The laboratory investigations were in agreement with the simulations. Thus, this work substantiated the fat-IBC signal transmission variability in the context of varying blood vessel configurations.
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| 2. |
- Asan, Noor Badariah, et al.
(författare)
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Characterization of the Fat Channel for Intra-Body Communication at R-Band Frequencies
- 2018
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 18:9
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the use of fat tissue as a communication channel between in-body, implanted devices at R-band frequencies (1.7–2.6 GHz). The proposed fat channel is based on an anatomical model of the human body. We propose a novel probe that is optimized to efficiently radiate the R-band frequencies into the fat tissue. We use our probe to evaluate the path loss of the fat channel by studying the channel transmission coefficient over the R-band frequencies. We conduct extensive simulation studies and validate our results by experimentation on phantom and ex-vivo porcine tissue, with good agreement between simulations and experiments. We demonstrate a performance comparison between the fat channel and similar waveguide structures. Our characterization of the fat channel reveals propagation path loss of ∼0.7 dB and ∼1.9 dB per cm for phantom and ex-vivo porcine tissue, respectively. These results demonstrate that fat tissue can be used as a communication channel for high data rate intra-body networks.
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| 3. |
- Asan, Noor Badariah, et al.
(författare)
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Data Packet Transmission through Fat Tissue for Wireless Intra-Body Networks
- 2017
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Ingår i: IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2469-7249 .- 2469-7257. ; 1:2, s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- This work explores high data rate microwave communication through fat tissue in order to address the wide bandwidth requirements of intra-body area networks. We have designed and carried out experiments on an IEEE 802.15.4 based WBAN prototype by measuring the performance of the fat tissue channel in terms of data packet reception with respect to tissue length and power transmission. This paper proposes and demonstrates a high data rate communication channel through fat tissue using phantom and ex-vivo environments. Here, we achieve a data packet reception of approximately 96 % in both environments. The results also show that the received signal strength drops by ~1 dBm per 10 mm in phantom and ~2 dBm per 10 mm in ex-vivo. The phantom and ex-vivo experimentations validated our approach for high data rate communication through fat tissue for intrabody network applications. The proposed method opens up new opportunities for further research in fat channel communication. This study will contribute to the successful development of high bandwidth wireless intra-body networks that support high data rate implanted, ingested, injected, or worn devices
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| 4. |
- Asan, Noor Badariah, 1984-, et al.
(författare)
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Effect of Thickness Inhomogeneity in Fat Tissue on In-Body Microwave Propagation
- 2018
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Ingår i: Proceedings of the 2018 IEEE/MTT-S International Microwave Biomedical Conference (IMBIOC). - Philadelphia, USA : IEEE. - 9781538659182 ; , s. 136-138
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Konferensbidrag (refereegranskat)abstract
- In recent studies, it has been found that fat tissue can be used as a microwave communication channel. In this article, the effect of thickness inhomogeneities in fat tissues on the performance of in-body microwave communication at 2.45 GHz is investigated using phantom models. We considered two models namely concave and convex geometrical fat distribution to account for the thickness inhomogeneities. The thickness of the fat tissue is varied from 5 mm to 45 mm and the Gap between the transmitter/receiver and the starting and ending of concavity/convexity is varied from 0 mm to 25 mm for a length of 100 mm to study the behavior in the microwave propagation. The phantoms of different geometries, concave and convex, are used in this work to validate the numerical studies. It was noticed that the convex model exhibited higher signal coupling by an amount of 1 dB (simulation) and 2 dB (measurement) compared to the concave model. From the study, it was observed that the signal transmission improves up to 30 mm thick fat and reaches a plateau when the thickness is increased further.
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| 5. |
- Asan, Noor Badariah, 1984-, et al.
(författare)
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Effects of Blood Vessels on Fat Channel Microwave Communication
- 2018
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Ingår i: 2018 IEEE Conference on Antenna Measurements & Applications (CAMA). - : IEEE. - 9781538657959
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Konferensbidrag (refereegranskat)abstract
- This study aims to investigate the reliability of intra-body microwave propagation through the fat tissue in presence of blood vessels. Here, we consider three types of blood vessels with different sizes. We investigate the impact of the number of blood vessels and their alignment on the transmission of microwave signals through the fat channel. In our study, we employ two probes that act as a transmitter and a receiver. The probes are designed to operate at the Industrial, Scientific, and Medical radio band (2.45 GHz). For a channel length of 100 mm, our results indicate that the presence of the blood vessels may increase the channel path loss by similar to 1.5 dB and similar to 4.5 dB when the vessels are aligned and orthogonally aligned with the fat channel, respectively.
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| 6. |
- Asan, Noor Badariah, 1984-, et al.
(författare)
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Intra-body microwave communication through adipose tissue
- 2017
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Ingår i: Healthcare technology letters. - : The Institution of Engineering and Technology. - 2053-3713. ; 4:4, s. 115-121
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Tidskriftsartikel (refereegranskat)abstract
- The human body can act as a medium for the transmission of electromagnetic waves in the wireless body sensor networks context. However, there are transmission losses in biological tissues due to the presence of water and salts. This Letter focuses on lateral intra-body microwave communication through different biological tissue layers and demonstrates the effect of the tissue thicknesses by comparing signal coupling in the channel. For this work, the authors utilise the R-band frequencies since it overlaps the industrial, scientific and medical radio (ISM) band. The channel model in human tissues is proposed based on electromagnetic simulations, validated using equivalent phantom and ex-vivo measurements. The phantom and ex-vivo measurements are compared with simulation modelling. The results show that electromagnetic communication is feasible in the adipose tissue layer with a low attenuation of approximate to 2 dB per 20 mm for phantom measurements and 4 dB per 20 mm for ex-vivo measurements at 2 GHz. Since the dielectric losses of human adipose tissues are almost half of ex-vivo tissue, an attenuation of around 3 dB per 20 mm is expected. The results show that human adipose tissue can be used as an intra-body communication channel.
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| 7. |
- Asan, Noor Badariah, 1984-, et al.
(författare)
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Reliability of the fat tissue channel for intra-body microwave communication
- 2017
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Ingår i: 2017 IEEE Conference on Antenna Measurements & Applications (CAMA). - : IEEE. - 9781509050284 ; , s. 310-313
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Konferensbidrag (refereegranskat)abstract
- Recently, the human fat tissue has been proposed as a microwave channel for intra-body sensor applications. In this work, we assess how disturbances can prevent reliable microwave propagation through the fat channel. Perturbants of different sizes are considered. The simulation and experimental results show that efficient communication through the fat channel is possible even in the presence of perturbants such as embedded muscle layers and blood vessels. We show that the communication channel is not affected by perturbants that are smaller than 15 mm cube.
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| 8. |
- Mattsson, Viktor, et al.
(författare)
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Machine Learning Powered Microwave Device for Local Body Composition Assessment
- 2023
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; , s. 1-1
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Tidskriftsartikel (refereegranskat)abstract
- In this paper a standalone microwave device is evaluated for its ability to assess local body composition with the ultimate goal to assess muscle quality. Data have been collected from volunteers who were measured on their thigh using the microwave device and ultrasound. A machine learning algorithm with three stages is designed that utilizes the stacked nature of the tissues in the thigh to predict skin and fat thickness and the cross-sectional area of the rectus femoris muscle. The input to the algorithm is the signal response from the microwave sensor and also the prediction from the previous layers. The ultrasound measurements are used as the ground truth labels for each tissue to train the machine learning models. The measurements were performed with two sensors, where usage of the combined data from both sensors produced the best results for fat and muscle, 0.57 and 0.63 in R 2 score, respectively. In the drop analysis, a step where a select proportion of the data is temporarily removed, the identified models showed increased scores with a larger amount of data available indicating the learning of the models improves with more data. Although the results are encouraging more data is ultimately needed to further study the algorithm.
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| 9. |
- Mattsson, Viktor, et al.
(författare)
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MAS : Standalone Microwave Resonator to Assess Muscle Quality
- 2021
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 21:16
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Tidskriftsartikel (refereegranskat)abstract
- Microwave-based sensing for tissue analysis is recently gaining interest due to advantages such as non-ionizing radiation and non-invasiveness. We have developed a set of transmission sensors for microwave-based real-time sensing to quantify muscle mass and quality. In connection, we verified the sensors by 3D simulations, tested them in a laboratory on a homogeneous three-layer tissue model, and collected pilot clinical data in 20 patients and 25 healthy volunteers. This report focuses on initial sensor designs for the Muscle Analyzer System (MAS), their simulation, laboratory trials and clinical trials followed by developing three new sensors and their performance comparison. In the clinical studies, correlation studies were done to compare MAS performance with other clinical standards, specifically the skeletal muscle index, for muscle mass quantification. The results showed limited signal penetration depth for the Split Ring Resonator (SRR) sensor. New sensors were designed incorporating Substrate Integrated Waveguides (SIW) and a bandstop filter to overcome this problem. The sensors were validated through 3D simulations in which they showed increased penetration depth through tissue when compared to the SRR. The second-generation sensors offer higher penetration depth which will improve clinical data collection and validation. The bandstop filter is fabricated and studied in a group of volunteers, showing more reliable data that warrants further continuation of this development.
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| 10. |
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| 11. |
- Mattsson, Viktor, et al.
(författare)
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Muscle Analyzer System : Exploring Correlation Between Novel Microwave Resonator and Ultrasound-based Tissue Information in the Thigh
- 2022
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Ingår i: 2022 16TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP). - : Institute of Electrical and Electronics Engineers (IEEE). - 9788831299046
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Konferensbidrag (refereegranskat)abstract
- A microwave sensor to safely measure quality of muscle tissue for diagnosis and screening of diseases and medical conditions characterized by fat infiltration in muscle is presented. Fat infiltration in muscle may be seen by a lower dielectric constant of muscle at microwave frequencies corresponding to the large contrast between fat and muscle tissues. A planar resonator based on a bandstop filter and optimized to noninvasively interrogate muscle in the thigh on tissue quality is proposed. Currently, a study based on clinical trials is carried out, and, here, we present a preliminary correlation between skin and fat thicknesses and rectus femoris cross sectional area (CSA) measured with ultrasound and the proposed sensor's resonance frequency. CST simulations based on the ultrasound information guide the analysis. We see that although there are signs of a potential correlation between CSA and resonance, skin and fat variability is still an issue to overcome.
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| 12. |
- Perez, Mauricio D., et al.
(författare)
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Microwave Sensors for New Approach in Monitoring Hip Fracture Healing
- 2017
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Ingår i: 2017 11th European Conference On Antennas And Propagation (EUCAP). - : IEEE. - 9788890701870 ; , s. 1838-1842
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Konferensbidrag (refereegranskat)abstract
- Cyber-Physical System (CPS) applications in lower-extremity bony-fracture rehabilitation systems require real-time biophysical data. Emerging and interesting solutions are microwave approaches that provide good contrast between hard and soft tissues and between local anomalies inside tissues. Preliminarily some contacting non-invasive planar methods have been investigated in their feasibility of detecting human tissues variations with promising results. In this work we introduce two new microwave planar sensors for a new approach of hip fracture healing follow-up tool. They are designed for improved resolution and penetration at frequencies between 1 to 3 GHz in detecting variations in bone, muscle or fat tissues that are expected during a rehabilitation process. The resonant devices are optimized using Frequency Domain Reflectometry and CST (R) environment and validated using clinical trials with volunteers. The new approach is validated using clinical trials with volunteers and patients. These outcomes further emphasize the feasibility of devising systems for fracture rehabilitation.
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| 13. |
- Prins, Jonne T H, et al.
(författare)
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Surgical stabilization of rib fractures versus nonoperative treatment in patients with multiple rib fractures following cardiopulmonary resuscitation: An international, retrospective matched case-control study.
- 2022
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Ingår i: The journal of trauma and acute care surgery. - 2163-0763. ; 93:6, s. 727-735
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Tidskriftsartikel (refereegranskat)abstract
- The presence of six or more rib fractures or a displaced rib fracture due to cardiopulmonary resuscitation (CPR) has been associated with longer hospital and intensive care unit (ICU) length of stay (LOS). Evidence on the effect of surgical stabilization of rib fractures (SSRF) following CPR is limited. This study aimed to evaluate outcomes after SSRF versus nonoperative management in patients with multiple rib fractures after CPR.An international, retrospective study was performed in patients who underwent SSRF or nonoperative management for multiple rib fractures following CPR between January 1, 2012, and July 31, 2020. Patients who underwent SSRF were matched to nonoperative controls by cardiac arrest location and cause, rib fracture pattern, and age. The primary outcome was ICU LOS.Thirty-nine operatively treated patient were matched to 66 nonoperatively managed controls with comparable CPR-related characteristics. Patients who underwent SSRF more often had displaced rib fractures (n = 28 [72%] vs. n = 31 [47%]; p = 0.015) and a higher median number of displaced ribs (2 [P 25 -P 75 , 0-3] vs. 0 [P 25 -P 75 , 0-3]; p = 0.014). Surgical stabilization of rib fractures was performed at a median of 5 days (P 25 -P 75 , 3-8 days) after CPR. In the nonoperative group, a rib fixation specialist was consulted in 14 patients (21%). The ICU LOS was longer in the SSRF group (13 days [P 25 -P 75 , 9-23 days] vs. 9 days [P 25 -P 75 , 5-15 days]; p = 0.004). Mechanical ventilator-free days, hospital LOS, thoracic complications, and mortality were similar.Despite matching, those who underwent SSRF over nonoperative management for multiple rib fractures following CPR had more severe consequential chest wall injury and a longer ICU LOS. A benefit of SSRF on in-hospital outcomes could not be demonstrated. A low consultation rate for rib fixation in the nonoperative group indicates that the consideration to perform SSRF in this population might be associated with other nonradiographic or injury-related variables.Therapeutic/Care Management; Level III.
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| 14. |
- Raaben, Marco, et al.
(författare)
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COMplex Fracture Orthopedic Rehabilitation (COMFORT) - Real-time visual biofeedback on weight bearing versus standard training methods in the treatment of proximal femur fractures in the elderly : study protocol for a multicenter randomized controlled trial
- 2018
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Ingår i: Trials. - : BioMed Central (BMC). - 1745-6215. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Background:Proximal femur fractures are a common injury after low energy trauma in the elderly. Most rehabilitation programs are based on restoring mobility and early resumption of weight-bearing. However, therapy compliance is low in patients following lower extremity fractures. Moreover, little is known about the relevance of gait parameters and how to steer the rehabilitation after proximal femur fractures in the elderly. Therefore, the aim of this prospective, randomized controlled trial is to gain insight in gait parameters and evaluate if real-time visual biofeedback can improve therapy compliance after proximal femur fractures in the elderly.Methods:This is a two-arm, parallel-design, prospective, randomized controlled trial. Inclusion criteria are age >= 60 years, a proximal femur fracture following low energy trauma, and unrestricted-weight bearing. Exclusion criteria are cognitive impairment and limited mobility before trauma. Participants are randomized into either the control group, which receives care as usual, or the intervention group, which receives real-time visual biofeedback about weight-bearing during gait in addition to care as usual. Spatiotemporal gait parameters will be measured in 94 participants per group during a 30-m walk with an ambulatory biofeedback system (SensiStep). The progress of rehabilitation will be evaluated by the primary outcome parameters maximum peak load and step duration in relation to the discharge date. Secondary outcome parameters include other spatiotemporal gait parameters in relation to discharge date. Furthermore, the gait parameters will be related to three validated clinical tests: Elderly Mobility Scale; Functional Ambulation Categories; and Visual Analogue Scale. The primary hypothesis is that participants in the intervention group will show improved and faster rehabilitation compared to the control group.Discussion: The first aim of this multicenter trial is to investigate the normal gait patterns after proximal femur fractures in the elderly. The use of biofeedback systems during rehabilitation after proximal femur fractures in the elderly is promising; therefore, the second aim is to investigate the effect of real-time visual biofeedback on gait after proximal femur fractures in the elderly. This could lead to improved outcome. In addition, analysis of the population may indicate characteristics of subgroups that benefit from feedback, making a differentiated approach in rehabilitation strategy possible.
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| 15. |
- Raaben, Marco, et al.
(författare)
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Innovative Measurement Of Rehabilitation Progress In Elderly With A Hip Fracture : A New Endpoint
- 2018
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Ingår i: 2018 IEEE Conference On Antenna Measurements & Applications (CAMA). - : IEEE. - 9781538657959
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Konferensbidrag (refereegranskat)abstract
- The worldwide ageing population leads to an increase in the incidence of hip fractures in elderly. Weight bearing is important to improve outcome, but rehabilitation is often hampered by the absence of proper rehabilitation tools. The aim of current study is to gain insight in important gait parameters and the rehabilitation progress of elderly with a hip fracture using an innovative biofeedback system (SensiStep). Force measurements were performed in 113 participants during a 30-meter walk with SensiStep. Also, two mobility tests and pain score were assessed in these participants. In 10 participants the measurements were repeated after one year follow up, and 40 healthy volunteers were measured. The parameters peak force and step duration improved towards the end of rehabilitation. A new and objective endpoint of rehabilitation emerges from these two parameters. Moreover, a differentiated approach in rehabilitation could be developed based on the first training session. This could lead to individual rehabilitation programs and thereby improved outcome after hip fractures in elderly.
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| 16. |
- Raaben, Marco, et al.
(författare)
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Real-time visual biofeedback during weight bearing improves therapy compliance in patients following lower extremity fractures
- 2018
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Ingår i: Gait & Posture. - : ELSEVIER IRELAND LTD. - 0966-6362 .- 1879-2219. ; 59, s. 206-210
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Tidskriftsartikel (refereegranskat)abstract
- Background: Individuals with lower extremity fractures are often instructed on how much weight to bear on the affected extremity. Previous studies have shown limited therapy compliance in weight bearing during rehabilitation. In this study we investigated the effect of real-time visual biofeedback on weight bearing in individuals with lower extremity fractures in two conditions: full weight bearing and touch-down weight bearing. Methods: 11 participants with full weight bearing and 12 participants with touch-down weight bearing after lower extremity fractures have been measured with an ambulatory biofeedback system. The participants first walked 15 m and the biofeedback system was only used to register the weight bearing. The same protocol was then repeated with real-time visual feedback during weight bearing. The participants could thereby adapt their loading to the desired level and improve therapy compliance. Results: In participants with full weight bearing, real-time visual biofeedback resulted in a significant increase in loading from 50.9 +/- 7.51% bodyweight (BW) without feedback to 63.2 +/- 6.74% BW with feedback (P=0.0016). In participants with touch-down weight bearing, the exerted lower extremity load decreased from 16.7 +/- 9.77 kg without feedback to 10.27 +/- 4.56 kg with feedback (P=0.0718). More important, the variance between individual steps significantly decreased after feedback (P=0.018). Conclusions: Ambulatory monitoring weight bearing after lower extremity fractures showed that therapy compliance is low, both in full and touch-down weight bearing. Real-time visual biofeedback resulted in significantly higher peak loads in full weight bearing and increased accuracy of individual steps in touch-down weight bearing. Real-time visual biofeedback therefore results in improved therapy compliance after lower extremity fractures.
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| 17. |
- Raaben, Marco, et al.
(författare)
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Technical Aspects and Validation of a New Biofeedback System for Measuring Lower Limb Loading in the Dynamic Situation
- 2017
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- Background: A variety of techniques for measuring lower limb loading exists, each with their own limitations. A new ambulatory biofeedback system was developed to overcome these limitations. In this study, we described the technical aspects and validated the accuracy of this system. Methods: A bench press was used to validate the system in the static situation. Ten healthy volunteers were measured by the new biofeedback system and a dual-belt instrumented treadmill to validate the system in the dynamic situation. Results: Bench press results showed that the sensor accurately measured peak loads up to 1000 N in the static situation. In the healthy volunteers, the load curves measured by the biofeedback system were similar to the treadmill. However, the peak loads and loading rates were lower in the biofeedback system in all participants at all speeds. Conclusions: Advanced sensor technologies used in the new biofeedback system resulted in highly accurate measurements in the static situation. The position of the sensor and the design of the biofeedback system should be optimized to improve results in the dynamic situation.
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| 18. |
- Redzwan Mohd Shah, Syaiful
(författare)
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Prospective Applications of Microwaves in Medicine : Microwave Sensors for Orthopedic Monitoring and Burn Depth Assessment
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, the use of microwave techniques for medical diagnostics has experienced impressive developments. It has demonstrated excellent competencies in various modalities such as using non-ionizing electromagnetic waves, providing non-invasive diagnoses, and having the ability to penetrate human tissues within the GHz range. However, due to anatomical, physiological, and biological variations in the human body, certain obstacles are present. Moreover, there are accuracy problems such as the absence of numerical models and experimental data, difficulty in conducting tests due to safety issues with human subjects, and also practical restrictions in clinical implementation. With the presence of these issues, a better understanding of the microwave technique is essential to further improve its medical application and to introduce alternative diagnostic methods that can detect and monitor various medical conditions in real time.The first part of this thesis focuses on measurement systems for the microwave technique in terms of sensor design and development, numerical analysis, permittivity measurement, and phantom fabrication. The aim is to investigate the feasibility of flexible systems with different fields of application including a microwave sensor system for measuring the healing progression of bone defects present in lower extremity trauma, bone regeneration in craniotomy for craniosynostosis treatments, and dielectric variation for burn injuries. The microwave sensor which utilizes the contrast in dielectric constant between various tissues was used as the primary sensor for the proposed application. This involved detailed optimization of the sensor for greater sensitivity. The experimental work carried out in the lab environment showed that the microwave sensor was able to detect the contrast in dielectric properties so that it can give an indication of the healing status for actual clinical scenarios.The second part of the thesis is making a significant step towards its practical implementation by establishing a system that can detect and monitor the rate of healing progression with fast data acquisition speed of microseconds, and developing an efficient user interface to convert raw microwave data into legible clinical information in terms of bone healing and burn injuries. As an extension to this thesis, clinical studies were conducted and ethical approval for conducting tests on human subjects was obtained for the development of a microwave medical system. The results showed a clear difference in healing progressions due to high detection capability in terms of dielectric properties of different human tissues. All of these contributions enable a portable system to complement existing medical applications with the aim of providing more advanced healthcare systems.
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| 19. |
- Redzwan, Syaiful, et al.
(författare)
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Analysis of Thickness Variation in Biological Tissues using Microwave Sensors for Health Monitoring Applications
- 2019
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Ingår i: IEEE Access. - 2169-3536. ; 7, s. 156033-156043
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Tidskriftsartikel (refereegranskat)abstract
- Microwave sensing technique is a possible and attractive alternative modality to standard Xrays,magnetic resonance imaging, and computed tomography methods for medical diagnostic applications.This technique is beneficial since it uses non-ionizing radiation and that can be potentially used for themicrowave healthcare system. The main purpose of this paper is to present a microwave sensing techniqueto analyze the variations in biological tissue thickness, considering the effect of physiological and biologicalproperties on microwave signals. With this goal, we have developed a two-port non-invasive sensor systemcomposed of two split ring resonators (SRRs) operating at an Industrial, Scientific, and Medical frequencyband of 2.45 GHz. The system is verified using the amplitude and phase of the transmitted signal in ex-vivomodels, representing different tissue thicknesses. Clinical applications such as the diagnosis of muscularatrophy can be benefitted from this study.
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| 20. |
- Redzwan, Syaiful, et al.
(författare)
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Split-Ring Resonator Sensor Penetration Depth Assessment Using In Vivo Microwave Reflectivity and Ultrasound Measurements for Lower Extremity Trauma Rehabilitation
- 2018
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 18:2
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Tidskriftsartikel (refereegranskat)abstract
- In recent research, microwave sensors have been used to follow up the recovery of lower extremity trauma patients. This is done mainly by monitoring the changes of dielectric properties of lower limb tissues such as skin, fat, muscle, and bone. As part of the characterization of the microwave sensor, it is crucial to assess the signal penetration in in vivo tissues. This work presents a new approach for investigating the penetration depth of planar microwave sensors based on the Split-Ring Resonator in the in vivo context of the femoral area. This approach is based on the optimization of a 3D simulation model using the platform of CST Microwave Studio and consisting of a sensor of the considered type and a multilayered material representing the femoral area. The geometry of the layered material is built based on information from ultrasound images and includes mainly the thicknesses of skin, fat, and muscle tissues. The optimization target is the measured S-11 parameters at the sensor connector and the fitting parameters are the permittivity of each layer of the material. Four positions in the femoral area (two at distal and two at thigh) in four volunteers are considered for the in vivo study. The penetration depths are finally calculated with the help of the electric field distribution in simulations of the optimized model for each one of the 16 considered positions. The numerical results show that positions at the thigh contribute the highest penetration values of up to 17.5 mm. This finding has a high significance in planning in vitro penetration depth measurements and other tests that are going to be performed in the future.
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