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Lee, D., Nowinski, D. & Augustine, R. (2018). A UWB sensor based on resistively-loaded dipole antenna for skull healing on cranial surgery phantom models. Microwave and optical technology letters (Print), 60(4), 897-905
Open this publication in new window or tab >>A UWB sensor based on resistively-loaded dipole antenna for skull healing on cranial surgery phantom models
2018 (English)In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 60, no 4, p. 897-905Article in journal (Refereed) Published
Abstract [en]

After craniotomy, the monitoring of the skull healing progression is strongly needed to take a proper medical intervention. The CT scans is however currently used for follow-up after craniotomy resulting in lack of an effective and safety problem. This research proposes an alternative for monitoring the skull healing using ultra-wide band (UWB) antenna. For the healing of the skull surgical defect, a compact resistively-loaded dipole antenna is designed and analyzed in terms of its performance in the time domain. The head phantoms having a wideband characteristic are fabricated and used as models for the skull healing process. To represent various mineralization stages, phantoms with various dielectric constants from hydrogel scaffold to the normal skull and their intermediate values are used. The UWB radar technique in the time domain is implemented in the healing process of skull injuries emulating cranial cavities that are made as part of craniosynostosis treatment. The measurement results at the defect area show that the variations in amplitude of the reflected pulse as the skull healing is progressed. The results obtained can contribute to the development of microwave-based techniques as a preliminary study of a proof concept before clinical trial in the healing process after cranial surgery.

Place, publisher, year, edition, pages
WILEY, 2018
Keywords
craniotomy, craniosynostosis, resistively-loaded dipole antenna, ultra-wideband (UWB) antennas
National Category
Surgery Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-350741 (URN)10.1002/mop.31077 (DOI)000426868400018 ()
Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2018-06-05Bibliographically approved
Peng, J., Peng, Z., Zhu, Z., Augustine, R., Mahmoud, M. M., Tang, H., . . . Jiang, T. (2018). Achieving ultra-high electromagnetic wave absorption by anchoring Co0.33Ni0.33Mn0.33Fe2O4 nanoparticles on graphene sheets using microwave-assisted polyol method. Ceramics International, 44(17), 21015-21026
Open this publication in new window or tab >>Achieving ultra-high electromagnetic wave absorption by anchoring Co0.33Ni0.33Mn0.33Fe2O4 nanoparticles on graphene sheets using microwave-assisted polyol method
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2018 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 44, no 17, p. 21015-21026Article in journal (Refereed) Published
Abstract [en]

The Co0.33Ni0.33Mn0.33Fe2O4/graphene nanocomposite for electromagnetic wave absorption was successfully synthesized from metal chlorides solutions and graphite powder by a simple and rapid microwave-assisted polyol method via anchoring the Co0.33Ni0.33Mn0.33Fe2O4 nanoparticles on the layered graphene sheets. The Fe3+, Co2+, Ni2+ and Mn2+ ions in the solutions were attracted by graphene oxide obtained from graphite and converted to the precursors Fe(OH)(3), Co(OH)(2), Ni(OH)(2), and Mn(OH)(2) under slightly alkaline conditions. After the transformations of the precursors to Co-Ni-Mn ferrites and conversion of graphene oxide to graphene under microwave irradiation at 170 degrees C in just 25 min, the Co0.33Ni0.33Mn0.33Fe2O4/graphene nanocomposite was prepared. The composition and structure of the nanocomposite were characterized by X-ray diffraction (XRD), inductive coupled plasma emission spectroscopy (ICP), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), transmission electron microscopy (TEM), etc. It was found that with the filling ratio of only 20 wt% and the thickness of 2.3 mm, the nanocomposite showed an ultra-wide effective absorption bandwidth (less than -10 dB) of 8.48 GHz (from 9.52 to 18.00 GHz) with the minimum reflection loss of - 24.29 dB. Compared to pure graphene sheets, Co0.33Ni0.33Mn0.33Fe2O4 nano particles and the counterparts reported in literature, the nanocomposite exhibited much better electromagnetic wave absorption, mainly attributed to strong wave attenuation, as a result of synergistic effects of dielectric loss, conductive loss and magnetic loss, and to good impedance matching. In view of its thin thickness, light weight and outstanding electromagnetic wave absorption property, the nanocomposite could be used as a very promising electromagnetic wave absorber.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2018
Keywords
Co-Ni-Mn ferrites, Graphene, Electromagnetic wave absorption, Reflection loss, Microwave-assisted polyol method
National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-369384 (URN)10.1016/j.ceramint.2018.08.137 (DOI)000448226900055 ()
Available from: 2019-01-15 Created: 2019-01-15 Last updated: 2019-01-15Bibliographically approved
Mathur, P., Kurup, D. G., Perez, M. D., Mohd Shah Redzwan, S., Velander, J. & Augustine, R. (2018). An Efficient Method for Computing the Interaction of Open Ended Circular Waveguide with a Layered Media. Progress In Electromagnetics Research Letters, 76, 55-61
Open this publication in new window or tab >>An Efficient Method for Computing the Interaction of Open Ended Circular Waveguide with a Layered Media
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2018 (English)In: Progress In Electromagnetics Research Letters, ISSN 1937-6480, Vol. 76, p. 55-61Article in journal (Refereed) Published
Abstract [en]

This article presents a new method for studying the near-field electromagnetic interaction between a dielectric filled open ended circular waveguide (OECW) and a layered dielectric structure. The proposed model is based on plane wave spectrum theory using a novel and computationally efficient two step integration method. The first integral, involving multiple singularities in the integration path, is efficiently solved using a deformed elliptical integration path which encircles the singularities of the integral. The infinite domain tail integral involving the slowly converging integrand is further solved using an efficient trigonometric transformation. The proposed OECW based method is capable of determining the unknown material properties of any layered dielectric medium, and hence finds application in nondestructive evaluation of materials.

Place, publisher, year, edition, pages
E M W PUBLISHING, 2018
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-363078 (URN)10.2528/PIERL18021602 (DOI)000441313000009 ()
Funder
VINNOVA
Available from: 2018-10-12 Created: 2018-10-12 Last updated: 2018-10-12Bibliographically approved
Asan, N. B., Hassan, E., Velander, J., Redzwan, S., Noreland, D., Blokhuis, T. J., . . . Augustine, R. (2018). Characterization of the Fat Channel for Intra-Body Communication at R-Band Frequencies. Sensors, 18(9), Article ID 2752.
Open this publication in new window or tab >>Characterization of the Fat Channel for Intra-Body Communication at R-Band Frequencies
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2018 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 9, article id 2752Article in journal (Refereed) Published
Abstract [en]

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 similar to 0.7 dB and similar to 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.

Keywords
intra-body communication, path loss, microwave probes, channel characterization, fat tissue, ex-vivo, phantom, dielectric properties, topology optimization
National Category
Computer Sciences Communication Systems
Identifiers
urn:nbn:se:uu:diva-369000 (URN)10.3390/s18092752 (DOI)000446940600011 ()30134629 (PubMedID)
Funder
VINNOVA, 2015-04159VINNOVA, 2017-03568Swedish Foundation for Strategic Research , RIT17-0020Swedish Research Council
Available from: 2018-12-14 Created: 2018-12-14 Last updated: 2018-12-14Bibliographically approved
Raaben, M., Redzwan, S., Augustine, R. & Blokhuis, T. J. (2018). 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. Trials, 19, Article ID 220.
Open this publication in new window or tab >>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 (English)In: Trials, ISSN 1745-6215, E-ISSN 1745-6215, Vol. 19, article id 220Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Proximal femur fracture, Weight-bearing, Biofeedback, Gait analysis, SensiStep, Fracture rehabilitation
National Category
Orthopaedics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-353203 (URN)10.1186/s13063-018-2612-9 (DOI)000429992800001 ()29650034 (PubMedID)
Available from: 2018-06-13 Created: 2018-06-13 Last updated: 2018-06-14Bibliographically approved
Dancila, D., Beuerle, B., Shah, U., Augustine, R., Gustafsson, A., Oberhammer, J. & Rydberg, A. (2018). Leaky Wave Antenna at 300 GHz in KTH’s Micromachined Waveguide Technology. In: : . Paper presented at AntennEMB Symposium, Lund, May 24-25, 2018.
Open this publication in new window or tab >>Leaky Wave Antenna at 300 GHz in KTH’s Micromachined Waveguide Technology
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2018 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Telecommunications
Identifiers
urn:nbn:se:uu:diva-369240 (URN)
Conference
AntennEMB Symposium, Lund, May 24-25, 2018
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-14Bibliographically approved
Raaben, M., Holtslag, H. R., Leenen, L. P. H., Augustine, R. & Blokhuis, T. J. (2018). Real-time visual biofeedback during weight bearing improves therapy compliance in patients following lower extremity fractures. Gait & Posture, 59, 206-210
Open this publication in new window or tab >>Real-time visual biofeedback during weight bearing improves therapy compliance in patients following lower extremity fractures
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2018 (English)In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 59, p. 206-210Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
ELSEVIER IRELAND LTD, 2018
Keywords
SensiStep, Gait monitoring, Biofeedback, Lower extremity, Weight-bearing
National Category
Orthopaedics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-342648 (URN)10.1016/j.gaitpost.2017.10.022 (DOI)000415235300037 ()29078134 (PubMedID)
Available from: 2018-02-28 Created: 2018-02-28 Last updated: 2018-03-08Bibliographically approved
Redzwan, S., Velander, J., Mathur, P., Perez, M. D., Asan, N. B., Kurup, D. G., . . . Augustine, R. (2018). Split-Ring Resonator Sensor Penetration Depth Assessment Using In Vivo Microwave Reflectivity and Ultrasound Measurements for Lower Extremity Trauma Rehabilitation. Sensors, 18(2), Article ID 636.
Open this publication in new window or tab >>Split-Ring Resonator Sensor Penetration Depth Assessment Using In Vivo Microwave Reflectivity and Ultrasound Measurements for Lower Extremity Trauma Rehabilitation
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2018 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 2, article id 636Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
Microwave measurement, ultrasound measurement, split-ring resonator, penetration depth, human lower extremity, sensor, model optimization, multilayered material, electric field distribution
National Category
Medical Equipment Engineering
Identifiers
urn:nbn:se:uu:diva-352995 (URN)10.3390/s18020636 (DOI)000427544000319 ()29466312 (PubMedID)
Funder
Swedish Research Council, 2017-04644
Available from: 2018-07-16 Created: 2018-07-16 Last updated: 2018-07-16Bibliographically approved
Asan, N. B., Carlos, P. P., Redzwan, S., Noreland, D., Hassan, E., Rydberg, A., . . . Augustine, R. (2017). Data Packet Transmission through Fat Tissue for Wireless Intra-Body Networks. IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology
Open this publication in new window or tab >>Data Packet Transmission through Fat Tissue for Wireless Intra-Body Networks
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2017 (English)In: IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology, ISSN 2469-7249Article in journal (Refereed) Epub ahead of print
Abstract [en]

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

Keywords
Intra-body communication, microwave, channel characterization, data packet, Software Defined Radio, GNU Radio, exvivo, phantom
National Category
Engineering and Technology Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-335351 (URN)10.1109/JERM.2017.2766561 (DOI)
Projects
Eurostars project under Grant E-9655-COMFORTSwedish Vinnova project under Grant BDAS (2015-04159)Swedish Vinnova project under Reliable, interoperable and secure communication for body network (2017-03568)
Funder
eSSENCE - An eScience CollaborationVINNOVA, 2015-04159VINNOVA, 2017-03568
Available from: 2017-12-04 Created: 2017-12-04 Last updated: 2017-12-05Bibliographically approved
Asan, N. B., Redzwan, S., Rydberg, A., Augustine, R., Noreland, D., Hassan, E. & Voigt, T. (2017). Human fat tissue: A microwave communication channel. In: Proc. 1st MTT-S International Microwave Bio Conference: . Paper presented at IMBIOC 2017, May 15–17, Gothenburg, Sweden. IEEE
Open this publication in new window or tab >>Human fat tissue: A microwave communication channel
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2017 (English)In: Proc. 1st MTT-S International Microwave Bio Conference, IEEE, 2017Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we present an approach for communication through human body tissue in the R-band frequency range. This study examines the ranges of microwave frequencies suitable for intra-body communication. The human body tissues are characterized with respect to their transmission properties using simulation modeling and phantom measurements. The variations in signal coupling with respect to different tissue thicknesses are studied. The simulation and phantom measurement results show that electromagnetic communication in the fat layer is viable with attenuation of approximately 2 dB per 20 mm. 

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
tissue characterization, transmission medium, biomedical sensor, channel model, phantom measurement
National Category
Medical Engineering
Identifiers
urn:nbn:se:uu:diva-335479 (URN)10.1109/IMBIOC.2017.7965801 (DOI)978-1-5386-1713-7 (ISBN)
Conference
IMBIOC 2017, May 15–17, Gothenburg, Sweden
Projects
Eurostars project (grant E-9655-COMFORT)Swedish Vinnova project (grant BDAS)eSSENCE
Available from: 2017-07-03 Created: 2017-12-05 Last updated: 2017-12-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2876-223X

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