Wideband Electromagnetic Body Phantoms for the Evaluation of Wireless Communications in the Microwave Spectrum

[ES] La constante evolución de la tecnología y la búsqueda de nuevas aplicaciones que mejoren la vida de las personas ha llevado a la incorporación de estas tecnologías en el organismo. Las redes inalámbricas de área corporal (WBAN) son un buen ejemplo de esto, que consisten en redes de comunicaciones ubicadas en el propio cuerpo, tanto en la superficie como implantadas en su interior mediante el uso de dispositivos inalámbricos. Estas redes utilizan el cuerpo humano como medio de transmisión, por lo que debe evaluarse la influencia del mismo sobre la propagación. Además, las nuevas generaciones de comunicaciones móviles se están moviendo hacia el uso de frecuencias cada vez más altas, como las ondas milimétricas, que son más sensibles a la presencia de cualquier objeto en el entorno, incluidos los humanos. La investigación y el diseño de antenas y dispositivos que tengan en cuenta el cuerpo humano requiere pruebas en el entorno donde se supone que deben usarse. Los fantomas se convierten en una herramienta para evaluar la transmisión de señales electromagnéticas en un medio equivalente al cuerpo para evitar la experimentación en humanos o animales. Además de eso, se puede estudiar la influencia de estas ondas electromagnéticas sobre los propios tejidos en cuanto a la tasa de absorción específica (SAR).[CA] L'evolució constant de la tecnologia i la recerca de noves aplicacions que milloren la vida de les persones ha portat a la incorporació d'aquestes tecnologies en l'organisme. Les xarxes sense fils d'àrea corporal (WBAN) són un bon exemple d'açò, que consisteixen en xarxes de comunicacions ubicades al propi cos, tant en la superfície com implantades en el seu interior mitjançant l'ús de dispositius sense fils. Aquestes xarxes empren el cos humà com a medi de transmissió, per la qual cosa se n'ha d'avaluar la influència sobre la propagació. A més, les noves generacions de comunicacions mòbils s'estan movent cap a l'ús de freqüències cada vegada més altes, com les ones mil·limètriques, que són més sensibles a la presència de qualsevol objecte en l'entorn, incloent-hi els humans. La investigació i el disseny d'antenes i dispositius que tinguen en compte el cos humà requereix proves en l'entorn on se suposa que han d'usar-se. Els fantomes esdevenen una eina per a avaluar la transmissió de senyals electromagnètics en un medi equivalent al cos per tal d'evitar l'experimentació en humans o animals. A més d'això, es pot estudiar la influència d'aquestes ones electromagnètiques sobre els teixits mateixos en relació amb la taxa d'absorció específica (SAR).[EN] The constant evolution of technology and the search for new applications that improve people's lives has led to the arrival of the incorporation of these technologies in the organism. Wireless body area networks (WBANs) are a good example of this, consisting of communications networks located in the body itself, both on the surface and implanted inside it through the use of wireless devices. These networks use the human body as the transmitting medium, so its influence over the propagation has to be assessed. Besides, new generations of mobile communications are moving towards the use of higher frequencies, as the millimetre waves, which are more sensitive to the presence of any object in the environment, including humans. The research and design of antennas and devices that take into account the human body requires testing in the environment where these are supposed to be used. Phantoms become a tool for evaluating the transmission of electromagnetic signals in a body-equivalent medium in order to avoid experimentation on humans or animals. In addition to that, the influence of these electromagnetic waves over the tissues themselves can be studied with regard to the specific absorption rate (SAR).This thesis has been possible thanks to the funding contribution of the Universitat Polit`ecnica de Val`encia through the PAID-01-16 programme. This work was also supported by the UPV-IIS La Fe programme (STUDER, 2016 and EMOTE, 2017). The research stay was supported by the European Union’s Erasmus+ funding programme under a traineeship grant.Castelló Palacios, S. (2019). Wideband Electromagnetic Body Phantoms for the Evaluation of Wireless Communications in the Microwave Spectrum [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/13218

Experimental Assessment of Time Reversal for In-Body to In-Body UWB Communications

[EN] The standard of in-body communications is limited to the use of narrowband systems. These systems are far from the high data rate connections achieved by other wireless telecommunication services today in force. The UWB frequency band has been proposed as a possible candidate for future in-body networks. However, the attenuation of body tissues at gigahertz frequencies could be a serious drawback. Experimental measurements for channel modeling are not easy to carry out, while the use of humans is practically forbidden. Sophisticated simulation tools could provide inaccurate results since they are not able to reproduce all the in-body channel conditions. Chemical solutions known as phantoms could provide a fair approximation of body tissues¿ behavior. In this work, the Time Reversal technique is assessed to increase the channel performance of in-body communications. For this task, a large volume of experimental measurements is performed at the low part of UWB spectrum (3.1-5.1 GHz) by using a highly accurate phantom-based measurement setup. This experimental setup emulates an in-body to in-body scenario, where all the nodes are implanted inside the body. Moreover, the in-body channel characteristics such as the path loss, the correlation in transmission and reception, and the reciprocity of the channel are assessed and discussed.This work was supported by the Programa de Ayudas de Investigacion y Desarrollo (PAID-01-16) from Universitat Politecnica de Valencia and by the Ministerio de Economia y Competitividad, Spain (TEC2014-60258-C2-1-R), by the European FEDER funds.Andreu-Estellés, C.; Garcia-Pardo, C.; Castelló-Palacios, S.; Cardona Marcet, N. (2018). Experimental Assessment of Time Reversal for In-Body to In-Body UWB Communications. Wireless Communications and Mobile Computing (Online). (8927107):1-12. https://doi.org/10.1155/2018/8927107S1128927107Fireman, Z. (2003). Diagnosing small bowel Crohn’s disease with wireless capsule endoscopy. Gut, 52(3), 390-392. doi:10.1136/gut.52.3.390Burri, H., & Senouf, D. (2009). Remote monitoring and follow-up of pacemakers and implantable cardioverter defibrillators. Europace, 11(6), 701-709. doi:10.1093/europace/eup110Scanlon, W. G., Burns, B., & Evans, N. E. (2000). Radiowave propagation from a tissue-implanted source at 418 MHz and 916.5 MHz. IEEE Transactions on Biomedical Engineering, 47(4), 527-534. doi:10.1109/10.828152Chavez-Santiago, R., Garcia-Pardo, C., Fornes-Leal, A., Valles-Lluch, A., Vermeeren, G., Joseph, W., … Cardona, N. (2015). Experimental Path Loss Models for In-Body Communications within 2.36-2.5 GHz. IEEE Journal of Biomedical and Health Informatics, 1-1. doi:10.1109/jbhi.2015.2418757Khaleghi, A., Chávez-Santiago, R., & Balasingham, I. (2010). Ultra-wideband pulse-based data communications for medical implants. IET Communications, 4(15), 1889. doi:10.1049/iet-com.2009.0692Khaleghi, A., Chávez-Santiago, R., & Balasingham, I. (2011). Ultra-wideband statistical propagation channel model for implant sensors in the human chest. IET Microwaves, Antennas & Propagation, 5(15), 1805. doi:10.1049/iet-map.2010.0537Kurup, D., Scarpello, M., Vermeeren, G., Joseph, W., Dhaenens, K., Axisa, F., … Vanfleteren, J. (2011). In-body path loss models for implants in heterogeneous human tissues using implantable slot dipole conformal flexible antennas. EURASIP Journal on Wireless Communications and Networking, 2011(1). doi:10.1186/1687-1499-2011-51Floor, P. A., Chavez-Santiago, R., Brovoll, S., Aardal, O., Bergsland, J., Grymyr, O.-J. H. N., … Balasingham, I. (2015). In-Body to On-Body Ultrawideband Propagation Model Derived From Measurements in Living Animals. IEEE Journal of Biomedical and Health Informatics, 19(3), 938-948. doi:10.1109/jbhi.2015.2417805Shimizu, Y., Anzai, D., Chavez-Santiago, R., Floor, P. A., Balasingham, I., & Wang, J. (2017). Performance Evaluation of an Ultra-Wideband Transmit Diversity in a Living Animal Experiment. IEEE Transactions on Microwave Theory and Techniques, 65(7), 2596-2606. doi:10.1109/tmtt.2017.2669039Anzai, D., Katsu, K., Chavez-Santiago, R., Wang, Q., Plettemeier, D., Wang, J., & Balasingham, I. (2014). Experimental Evaluation of Implant UWB-IR Transmission With Living Animal for Body Area Networks. IEEE Transactions on Microwave Theory and Techniques, 62(1), 183-192. doi:10.1109/tmtt.2013.2291542Chou, C.-K., Chen, G.-W., Guy, A. W., & Luk, K. H. (1984). Formulas for preparing phantom muscle tissue at various radiofrequencies. Bioelectromagnetics, 5(4), 435-441. doi:10.1002/bem.2250050408Cheung, A. Y., & Koopman, D. W. (1976). Experimental Development of Simulated Biomaterials for Dosimetry Studies of Hazardous Microwave Radiation (Short Papers). IEEE Transactions on Microwave Theory and Techniques, 24(10), 669-673. doi:10.1109/tmtt.1976.1128936YAMAMOTO, H., ZHOU, J., & KOBAYASHI, T. (2008). Ultra Wideband Electromagnetic Phantoms for Antennas and Propagation Studies. IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E91-A(11), 3173-3182. doi:10.1093/ietfec/e91-a.11.3173Lazebnik, M., Madsen, E. L., Frank, G. R., & Hagness, S. C. (2005). Tissue-mimicking phantom materials for narrowband and ultrawideband microwave applications. Physics in Medicine and Biology, 50(18), 4245-4258. doi:10.1088/0031-9155/50/18/001Yilmaz, T., Foster, R., & Hao, Y. (2014). Broadband Tissue Mimicking Phantoms and a Patch Resonator for Evaluating Noninvasive Monitoring of Blood Glucose Levels. IEEE Transactions on Antennas and Propagation, 62(6), 3064-3075. doi:10.1109/tap.2014.2313139Gezici, S., Zhi Tian, Giannakis, G. B., Kobayashi, H., Molisch, A. F., Poor, H. V., & Sahinoglu, Z. (2005). Localization via ultra-wideband radios: a look at positioning aspects for future sensor networks. IEEE Signal Processing Magazine, 22(4), 70-84. doi:10.1109/msp.2005.1458289Marinova, M., Thielens, A., Tanghe, E., Vallozzi, L., Vermeeren, G., Joseph, W., … Martens, L. (2015). Diversity Performance of Off-Body MB-OFDM UWB-MIMO. IEEE Transactions on Antennas and Propagation, 63(7), 3187-3197. doi:10.1109/tap.2015.2422353SHI, J., ANZAI, D., & WANG, J. (2012). Channel Modeling and Performance Analysis of Diversity Reception for Implant UWB Wireless Link. IEICE Transactions on Communications, E95.B(10), 3197-3205. doi:10.1587/transcom.e95.b.3197Pajusco, P., & Pagani, P. (2009). On the Use of Uniform Circular Arrays for Characterizing UWB Time Reversal. IEEE Transactions on Antennas and Propagation, 57(1), 102-109. doi:10.1109/tap.2008.2009715Chavez-Santiago, R., Sayrafian-Pour, K., Khaleghi, A., Takizawa, K., Wang, J., Balasingham, I., & Li, H.-B. (2013). Propagation models for IEEE 802.15.6 standardization of implant communication in body area networks. IEEE Communications Magazine, 51(8), 80-87. doi:10.1109/mcom.2013.6576343Andreu, C., Castello-Palacios, S., Garcia-Pardo, C., Fornes-Leal, A., Valles-Lluch, A., & Cardona, N. (2016). Spatial In-Body Channel Characterization Using an Accurate UWB Phantom. IEEE Transactions on Microwave Theory and Techniques, 64(11), 3995-4002. doi:10.1109/tmtt.2016.2609409Pahlavan, K., & Levesque, A. H. (2005). Wireless Information Networks. doi:10.1002/0471738646Qiu, R. C., Zhou, C., Guo, N., & Zhang, J. Q. (2006). Time Reversal With MISO for Ultrawideband Communications: Experimental Results. IEEE Antennas and Wireless Propagation Letters, 5, 269-273. doi:10.1109/lawp.2006.875888Ando, H., Takizawa, K., Yoshida, T., Matsushita, K., Hirata, M., & Suzuki, T. (2016). Wireless Multichannel Neural Recording With a 128-Mbps UWB Transmitter for an Implantable Brain-Machine Interfaces. IEEE Transactions on Biomedical Circuits and Systems, 10(6), 1068-1078. doi:10.1109/tbcas.2016.251452

Development and Characterization of Polyester and Acrylate-Based Composites with Hydroxyapatite and Halloysite Nanotubes for Medical Applications

[EN] We aimed to study the distribution of hydroxyapatite (HA) and halloysite nanotubes (HNTs) as fillers and their influence on the hydrophobic character of conventional polymers used in the biomedical field. The hydrophobic polyester poly (¿-caprolactone) (PCL) was blended with its more hydrophilic counterpart poly (lactic acid) (PLA) and the hydrophilic acrylate poly (2-hydroxyethyl methacrylate) (PHEMA) was analogously compared to poly (ethyl methacrylate) (PEMA) and its copolymer. The addition of HA and HNTs clearly improve surface wettability in neat samples (PCL and PHEMA), but not that of the corresponding binary blends. Energy-dispersive X-ray spectroscopy mapping analyses show a homogenous distribution of HA with appropriate Ca/P ratios between 1.3 and 2, even on samples that were incubated for seven days in simulated body fluid, with the exception of PHEMA, which is excessively hydrophilic to promote the deposition of salts on its surface. HNTs promote large aggregates on more hydrophilic polymers. The degradation process of the biodegradable polyester PCL blended with PLA, and the addition of HA and HNTs, provide hydrophilic units and decrease the overall crystallinity of PCL. Consequently, after 12 weeks of incubation in phosphate buffered saline the mass loss increases up to 48% and mechanical properties decrease above 60% compared with the PCL/PLA blend.Dominguez-Candela thanks the Universitat Politècnica de València for the financial support through an FPI-UPV grant (PAID-01-19)Torres, E.; Domínguez-Candela, I.; Castelló-Palacios, S.; Vallés Lluch, A.; Fombuena, V. (2020). Development and Characterization of Polyester and Acrylate-Based Composites with Hydroxyapatite and Halloysite Nanotubes for Medical Applications. Polymers. 12(8):1-13. https://doi.org/10.3390/polym12081703S113128Noyama, Y., Miura, T., Ishimoto, T., Itaya, T., Niinomi, M., & Nakano, T. (2012). Bone Loss and Reduced Bone Quality of the Human Femur after Total Hip Arthroplasty under Stress-Shielding Effects by Titanium-Based Implant. MATERIALS TRANSACTIONS, 53(3), 565-570. doi:10.2320/matertrans.m2011358Temple, J. P., Hutton, D. L., Hung, B. P., Huri, P. Y., Cook, C. A., Kondragunta, R., … Grayson, W. L. (2014). Engineering anatomically shaped vascularized bone grafts with hASCs and 3D-printed PCL scaffolds. Journal of Biomedical Materials Research Part A, n/a-n/a. doi:10.1002/jbm.a.35107Lee, K. H., Kim, H. Y., Khil, M. S., Ra, Y. M., & Lee, D. R. (2003). Characterization of nano-structured poly(ε-caprolactone) nonwoven mats via electrospinning. Polymer, 44(4), 1287-1294. doi:10.1016/s0032-3861(02)00820-0Li, X., Cui, R., Sun, L., Aifantis, K. E., Fan, Y., Feng, Q., … Watari, F. (2014). 3D-Printed Biopolymers for Tissue Engineering Application. International Journal of Polymer Science, 2014, 1-13. doi:10.1155/2014/829145Washington, K. E., Kularatne, R. N., Karmegam, V., Biewer, M. C., & Stefan, M. C. (2016). Recent advances in aliphatic polyesters for drug delivery applications. WIREs Nanomedicine and Nanobiotechnology, 9(4). doi:10.1002/wnan.1446Venkatesan, J., & Kim, S.-K. (2014). Nano-Hydroxyapatite Composite Biomaterials for Bone Tissue Engineering—A Review. Journal of Biomedical Nanotechnology, 10(10), 3124-3140. doi:10.1166/jbn.2014.1893Chen, G.-Q., & Wu, Q. (2005). The application of polyhydroxyalkanoates as tissue engineering materials. Biomaterials, 26(33), 6565-6578. doi:10.1016/j.biomaterials.2005.04.036Rezwan, K., Chen, Q. Z., Blaker, J. J., & Boccaccini, A. R. (2006). Biodegradable and bioactive porous polymer/inorganic composite scaffolds for bone tissue engineering. Biomaterials, 27(18), 3413-3431. doi:10.1016/j.biomaterials.2006.01.039Lowry, K. J., Hamson, K. R., Bear, L., Peng, Y. B., Calaluce, R., Evans, M. L., … Allen, W. C. (1997). Polycaprolactone/glass bioabsorbable implant in a rabbit humerus fracture model. Journal of Biomedical Materials Research, 36(4), 536-541. doi:10.1002/(sici)1097-4636(19970915)36:43.0.co;2-8Corden, T. J., Jones, I. A., Rudd, C. D., Christian, P., Downes, S., & McDougall, K. E. (2000). Physical and biocompatibility properties of poly-ε-caprolactone produced using in situ polymerisation: a novel manufacturing technique for long-fibre composite materials. Biomaterials, 21(7), 713-724. doi:10.1016/s0142-9612(99)00236-7Onal, L., Cozien-Cazuc, S., Jones, I. A., & Rudd, C. D. (2007). Water absorption properties of phosphate glass fiber-reinforced poly-ε-caprolactone composites for craniofacial bone repair. Journal of Applied Polymer Science, 107(6), 3750-3755. doi:10.1002/app.27518Ahmed, I., Parsons, A. J., Palmer, G., Knowles, J. C., Walker, G. S., & Rudd, C. D. (2008). Weight loss, ion release and initial mechanical properties of a binary calcium phosphate glass fibre/PCL composite. Acta Biomaterialia, 4(5), 1307-1314. doi:10.1016/j.actbio.2008.03.018Gough, J. E., Christian, P., Scotchford, C. A., Rudd, C. D., & Jones, I. A. (2001). Synthesis, degradation, andin vitro cell responses of sodium phosphate glasses for craniofacial bone repair. Journal of Biomedical Materials Research, 59(3), 481-489. doi:10.1002/jbm.10020Gough, J. E., Christian, P., Unsworth, J., Evans, M. P., Scotchford, C. A., & Jones, I. A. (2004). Controlled degradation and macrophage responses of a fluoride-treated polycaprolactone. Journal of Biomedical Materials Research, 69A(1), 17-25. doi:10.1002/jbm.a.20072Choi, W.-Y., Kim, H.-E., & Koh, Y.-H. (2012). Production, mechanical properties and in vitro biocompatibility of highly aligned porous poly(ε-caprolactone) (PCL)/hydroxyapatite (HA) scaffolds. Journal of Porous Materials, 20(4), 701-708. doi:10.1007/s10934-012-9644-4Yeo, M. G., & Kim, G. H. (2011). Preparation and Characterization of 3D Composite Scaffolds Based on Rapid-Prototyped PCL/β-TCP Struts and Electrospun PCL Coated with Collagen and HA for Bone Regeneration. Chemistry of Materials, 24(5), 903-913. doi:10.1021/cm201119qSalerno, A., Zeppetelli, S., Di Maio, E., Iannace, S., & Netti, P. A. (2011). Design of Bimodal PCL and PCL-HA Nanocomposite Scaffolds by Two Step Depressurization During Solid-state Supercritical CO2 Foaming. Macromolecular Rapid Communications, 32(15), 1150-1156. doi:10.1002/marc.201100119Jackson, I. T., & Yavuzer, R. (2000). Hydroxyapatite cement: an alternative for craniofacial skeletal contour refinements. British Journal of Plastic Surgery, 53(1), 24-29. doi:10.1054/bjps.1999.3236Miller, L., Guerra, A. B., Bidros, R. S., Trahan, C., Baratta, R., & Metzinger, S. E. (2005). A Comparison of Resistance to Fracture Among Four Commercially Available Forms of Hydroxyapatite Cement. Annals of Plastic Surgery, 55(1), 87-92. doi:10.1097/01.sap.0000162510.05196.c6Lawson, E. E., Barry, B. W., Williams, A. C., & Edwards, H. G. M. (1997). Biomedical Applications of Raman Spectroscopy. Journal of Raman Spectroscopy, 28(2-3), 111-117. doi:10.1002/(sici)1097-4555(199702)28:2/33.0.co;2-zLoty, C., Sautier, J.-M., Boulekbache, H., Kokubo, T., Kim, H.-M., & Forest, N. (2000). In vitro bone formation on a bone-like apatite layer prepared by a biomimetic process on a bioactive glass-ceramic. Journal of Biomedical Materials Research, 49(4), 423-434. doi:10.1002/(sici)1097-4636(20000315)49:43.0.co;2-7Roach, P., Eglin, D., Rohde, K., & Perry, C. C. (2007). Modern biomaterials: a review—bulk properties and implications of surface modifications. Journal of Materials Science: Materials in Medicine, 18(7), 1263-1277. doi:10.1007/s10856-006-0064-3Torres, E., Vallés-Lluch, A., Fombuena, V., Napiwocki, B., & Lih-Sheng, T. (2017). Influence of the Hydrophobic-Hydrophilic Nature of Biomedical Polymers and Nanocomposites on In Vitro Biological Development. Macromolecular Materials and Engineering, 302(12), 1700259. doi:10.1002/mame.201700259Chen, B., & Sun, K. (2005). Mechanical and dynamic viscoelastic properties of hydroxyapatite reinforced poly(ε-caprolactone). Polymer Testing, 24(8), 978-982. doi:10.1016/j.polymertesting.2005.07.013Heo, S.-J., Kim, S.-E., Wei, J., Hyun, Y.-T., Yun, H.-S., Kim, D.-H., … Shin, J.-W. (2008). Fabrication and characterization of novel nano- and micro-HA/PCL composite scaffolds using a modified rapid prototyping process. Journal of Biomedical Materials Research Part A, 9999A, NA-NA. doi:10.1002/jbm.a.31726Lee, K.-S., & Chang, Y.-W. (2012). Thermal, mechanical, and rheological properties of poly(ε-caprolactone)/halloysite nanotube nanocomposites. Journal of Applied Polymer Science, 128(5), 2807-2816. doi:10.1002/app.38457Liu, M., Guo, B., Du, M., Lei, Y., & Jia, D. (2007). Natural inorganic nanotubes reinforced epoxy resin nanocomposites. Journal of Polymer Research, 15(3), 205-212. doi:10.1007/s10965-007-9160-4Zhou, W. Y., Guo, B., Liu, M., Liao, R., Rabie, A. B. M., & Jia, D. (2009). Poly(vinyl alcohol)/halloysite nanotubes bionanocomposite films: Properties and in vitro osteoblasts and fibroblasts response. Journal of Biomedical Materials Research Part A, n/a-n/a. doi:10.1002/jbm.a.32656Xue, W., Bandyopadhyay, A., & Bose, S. (2009). Mesoporous calcium silicate for controlled release of bovine serum albumin protein. Acta Biomaterialia, 5(5), 1686-1696. doi:10.1016/j.actbio.2009.01.012Torres, E., Fombuena, V., Vallés-Lluch, A., & Ellingham, T. (2017). Improvement of mechanical and biological properties of Polycaprolactone loaded with Hydroxyapatite and Halloysite nanotubes. Materials Science and Engineering: C, 75, 418-424. doi:10.1016/j.msec.2017.02.087Abe, Y., Kokubo, T., & Yamamuro, T. (1990). Apatite coating on ceramics, metals and polymers utilizing a biological process. Journal of Materials Science: Materials in Medicine, 1(4), 233-238. doi:10.1007/bf00701082Kokubo, T., & Takadama, H. (2006). How useful is SBF in predicting in vivo bone bioactivity? Biomaterials, 27(15), 2907-2915. doi:10.1016/j.biomaterials.2006.01.017Xue, L., & Greisler, H. P. (2003). Biomaterials in the development and future of vascular grafts. Journal of Vascular Surgery, 37(2), 472-480. doi:10.1067/mva.2003.88Kim, H.-M., Kishimoto, K., Miyaji, F., Kokubo, T., Yao, T., Suetsugu, Y., … Nakamura, T. (1999). Composition and structure of the apatite formed on PET substrates in SBF modified with various ionic activity products. Journal of Biomedical Materials Research, 46(2), 228-235. doi:10.1002/(sici)1097-4636(199908)46:23.0.co;2-jTAKADAMA, H., KIM, H.-M., MIYAJI, F., KOKUBO, T., & NAKAMURA, T. (2000). Mechanism of Apatite Formation Induced by Silanol Groups. TEM observation. Journal of the Ceramic Society of Japan, 108(1254), 118-121. doi:10.2109/jcersj.108.1254_118Vallés Lluch, A., Gallego Ferrer, G., & Monleón Pradas, M. (2009). Biomimetic apatite coating on P(EMA-co-HEA)/SiO2 hybrid nanocomposites. Polymer, 50(13), 2874-2884. doi:10.1016/j.polymer.2009.04.022HUTCHENS, S., BENSON, R., EVANS, B., ONEILL, H., & RAWN, C. (2006). Biomimetic synthesis of calcium-deficient hydroxyapatite in a natural hydrogel. Biomaterials, 27(26), 4661-4670. doi:10.1016/j.biomaterials.2006.04.032Kim, H.-M., Himeno, T., Kawashita, M., Kokubo, T., & Nakamura, T. (2004). The mechanism of biomineralization of bone-like apatite on synthetic hydroxyapatite: an in vitro assessment. Journal of The Royal Society Interface, 1(1), 17-22. doi:10.1098/rsif.2004.0003Azzopardi, P. V., O’Young, J., Lajoie, G., Karttunen, M., Goldberg, H. A., & Hunter, G. K. (2010). Roles of Electrostatics and Conformation in Protein-Crystal Interactions. PLoS ONE, 5(2), e9330. doi:10.1371/journal.pone.0009330Hynes, R. O. (1992). Integrins: Versatility, modulation, and signaling in cell adhesion. Cell, 69(1), 11-25. doi:10.1016/0092-8674(92)90115-sWassell, D. T. H., Hall, R. C., & Embery, G. (1995). Adsorption of bovine serum albumin onto hydroxyapatite. Biomaterials, 16(9), 697-702. doi:10.1016/0142-9612(95)99697-kZhou, H., Wu, T., Dong, X., Wang, Q., & Shen, J. (2007). Adsorption mechanism of BMP-7 on hydroxyapatite (001) surfaces. Biochemical and Biophysical Research Communications, 361(1), 91-96. doi:10.1016/j.bbrc.2007.06.169Middleton, J. C., & Tipton, A. J. (2000). Synthetic biodegradable polymers as orthopedic devices. Biomaterials, 21(23), 2335-2346. doi:10.1016/s0142-9612(00)00101-0Li, H., Chen, Y., & Xie, Y. (2003). Photo-crosslinking polymerization to prepare polyanhydride/needle-like hydroxyapatite biodegradable nanocomposite for orthopedic application. Materials Letters, 57(19), 2848-2854. doi:10.1016/s0167-577x(02)01386-1Albertsson, A.-C., & Varma, I. K. (2002). Aliphatic Polyesters: Synthesis, Properties and Applications. Degradable Aliphatic Polyesters, 1-40. doi:10.1007/3-540-45734-8_

Initial UWB in-body channel characterization using a novel multilayer phantom measurement setup

[EN] Wireless Body Area Networks (WBANs) are a promising technology for medical purposes. Currently the WBAN are classified into: implanted (in-), surface (on-) or outside (off-) body communications regarding the location of the devices with reference to the human body. The Ultra Wide-Band (UWB) frequency band is growing as a band of interest for implanted communications because of its high data rate and low power consumption among other benefits. Software simulations, in-vivo measurements and experimental phantom measurements are common methods to properly characterize the propagation channel. Nevertheless, up to now, experimental phantoms measurements presented in the literature show some inconveniences, i.e., the accuracy of the phantoms compared with the real human tissues or the testbed used for the measurements. This paper aims at overcoming these issues using accurate phantoms designed for the purpose of implanted communications in the UWB frequency band. In addition, a multilayer phantom container was developed. This container has capacity for two different phantoms, emulating a heterogeneous propagation medium for in-body measurements. Moreover, a novel setup was built for in-body phantom measurements. As a result, an experimental path loss model is presented from the measurements obtained with phantoms. Besides, software simulations mimicking the experimental setup are performed in order to validate the previous results obtainedThis work was supported by the European Union's H2020:MSCA:ITN program for the "Wireless In-body Environment Communication-WiBEC" project under the grant agreement no. 675353. this work was also funded by the Programa de Ayudas de Investigación y Desarrollo 8PAID-01-16) from Univeristat Politècnica de València and by the Ministerio de Economía y Competitividad, Spain (TEC2014-60258-C2-1-R), by the European FEDER funds.Pérez-Simbor, S.; Barbi, M.; Garcia-Pardo, C.; Castelló-Palacios, S.; Cardona Marcet, N. (2018). Initial UWB in-body channel characterization using a novel multilayer phantom measurement setup. IEEE. 384-389. https://doi.org/10.1109/WCNCW.2018.8369011S38438

Wideband phantoms of different body tissues for heterogeneous models in body area networks

[EN] One of the key issues about wireless technologies is their interaction with the human body. The so-called internet of things will comprise many devices that will transmit either around or through the human body. These devices must be tested either in their working medium, when possible, or in the most realistic one. For this purpose, tissue-like phantoms are the best alternative to carry out realistic analyses of the performance of body area networks. In addition, they are the conventional way to certify the compliance of commercial standards by these devices. However, the number of phantoms that work in large bandwidths is limited in literature. This work aims at presenting chemical solutions that will be useful to prepare a variety of wideband tissue phantoms. Besides, the colon was mimicked in two ways, the healthy tissue and the malignant one, taking into account studies that relate changes on the relative permittivity with cancer. They were designed on the basis of acetonitrile in aqueous solutions as described in a previous work. Thus, many scenarios could be developed such as multilayers which imitate parts of the heterogeneous body.Research supported by the Programa de Ayudas de Investigación y Desarrollo (PAID-01-16) from Universitat Politècnica de València, by the Ministerio de Economía y Competitividad, Spain (TEC2014-60258-C2-1- R) and by the European FEDER Funds.Castelló-Palacios, S.; Garcia-Pardo, C.; Fornés Leal, A.; Cardona Marcet, N.; Vallés Lluch, A. (2018). Wideband phantoms of different body tissues for heterogeneous models in body area networks. IEEE. 3032-3035. https://doi.org/10.1109/EMBC.2017.8037496S3032303

Frequency Dependence of UWB In-Body Radio Channel Characteristics

(c) 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.[EN] In this letter, a research of ultra-wideband in-body channel by using a high accurate phantom is performed in order to evaluate the impact of frequency dependence of human tissues on the channel characteristics. Hence, a phantom-based measurement campaign from 3.1 to 5.1 GHz has been conducted. From postprocessing data, the path loss is assessed considering subbands of 500 MHz as well as the entire frequency range under test. In addition, the correlation in transmission is computed and discussed.This work was supported in part by the Ministerio de Economia y Competitividad, Spain, under Grant TEC2014-60258-C2-1-R, and in part by the European FEDER funds. (Corresponding author: Carlos Andreu.)Andreu-Estellés, C.; Garcia-Pardo, C.; Castelló-Palacios, S.; Vallés Lluch, A.; Cardona Marcet, N. (2018). Frequency Dependence of UWB In-Body Radio Channel Characteristics. IEEE Microwave and Wireless Components Letters. 28(4):359-361. https://doi.org/10.1109/LMWC.2018.2808427S35936128

Accurate broadband measurement of electromagnetic tissue phantoms using open-ended coaxial systems

[EN] New technologies and devices for wireless communication networks are continually developed. In order to assess their performance, they have to be tested in realistic environments taking into account the influence of the body in wireless communications. Thus, the development of phantoms, which are synthetic materials that can emulate accurately the electromagnetic behaviour of different tissues, is mandatory. An accurate dielectric measurement of these phantoms requires using a measurement method with a low uncertainty. The open-ended coaxial technique is the most spread technique but its accuracy is strongly conditioned by the calibration procedure. A typical calibration is performed using an open circuit, a short circuit and water. However, this basic calibration is not the most accurate approach for measuring all kinds of materials. In this paper, an uncertainty analysis of the calibration process of open-ended coaxial characterization systems when a polar liquid is added to the typical calibration is provided. Measurements are performed on electromagnetically well-known liquids in the 0.5 - 8.5 GHz band. Results show that adding methanol improves the accuracy in the whole solution domain of the system, mainly when measuring phantoms that mimic high water content tissues, whereas ethanol is more suitable for measuring low water content tissue phantoms.This work was supported by the Ministerio de Educacion y Ciencia, Spain (ref. TEC2014-60258-C2-1-R, TEC2014-56469-REDT), by the European FEDER funds.Fornés Leal, A.; Garcia-Pardo, C.; Castelló-Palacios, S.; Vallés Lluch, A.; Cardona Marcet, N. (2007). Accurate broadband measurement of electromagnetic tissue phantoms using open-ended coaxial systems. IEEE. 32-36. https://doi.org/10.1109/ISMICT.2017.7891761S323

Tailor-Made Tissue Phantoms Based on Acetonitrile Solutions for Microwave Applications up to 18 GHz

(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Tissue-equivalent phantoms play a key role in the development of new wireless communication devices that are tested on such phantoms prior to their commercialization. However, existing phantoms cover a small number of tissues and do not reproduce them accurately within wide frequency bands. This paper aims at enlarging the number of mimicked tissues as well as their working frequency band. Thus, a variety of potential compounds are scanned according to their relative permittivity from 0.5 to 18 GHz. Next, a combination of these compounds is characterized so the relation between their dielectric properties and composition is provided. Finally, taking advantage of the previous analysis, tailor-made phantoms are developed for different human tissues up to 18 GHz and particularized for the main current body area network (BAN) operating bands. The tailor-made phantoms presented here exhibit such a high accuracy as would allow researchers and manufacturers to test microwave devices at high frequencies for large bandwidths as well as the use of heterogeneous phantoms in the near future. The key to these phantoms lies in the incorporation of acetonitrile to aqueous solutions. Such compounds have a suitable behavior to achieve the relative permittivity values of body tissues within the studied frequency band.This work was supported by the Ministerio de Economia y Competitividad, Spain (TEC2014-60258-C2-1-R) and by the European FEDER Funds.Castelló-Palacios, S.; García Pardo, C.; Fornés Leal, A.; Cardona Marcet, N.; Vallés Lluch, A. (2016). Tailor-Made Tissue Phantoms Based on Acetonitrile Solutions for Microwave Applications up to 18 GHz. IEEE Transactions on Microwave Theory and Techniques. 64(11):3987-3994. https://doi.org/10.1109/TMTT.2016.2608890S39873994641

Formulas for easy-to-prepare tailored phantoms at 2.4 GHz ISM band

[EN] Emerging integration of communication networks into wearable or implantable body devices involves a challenge due to the transmitting medium, the body itself. This medium is heterogeneous and lossier than air, so devices that are supposed to work on it should be tested in tissue-equivalent materials. A number of materials with the electromagnetic response of body tissues have been proposed. Most of them are sucrose aqueous solutions that are supposed to simulate human's muscle tissue mainly within medical frequency bands. However, these recipes are restricted to a single tissue and it is difficult to adapt them to fit the permittivity values of different body tissues. The significance of this study lies in the development of a mathematical relationship that models the dielectric properties of an aqueous solution according to the concentration of sugar and salt at 2.4 GHz, the frequency around which an Industrial, Scientific and Medical (ISM) band is placed. Thus, it becomes possible to create custom-made phantoms with simple and accessible ingredients that are easy to prepare in any laboratory.This work was supported by the Ministerio de Economia y Competitividad, Spain (TEC2014-60258-C2-1-R) and by the European FEDER Funds.Castelló-Palacios, S.; Garcia-Pardo, C.; Fornés Leal, A.; Cardona Marcet, N.; Vallés Lluch, A. (2017). Formulas for easy-to-prepare tailored phantoms at 2.4 GHz ISM band. IEEE. 27-31. https://doi.org/10.1109/ISMICT.2017.7891760S273

Gel Phantoms for Body Microwave Propagation in the (2 to 26.5) GHz Frequency Band

[EN] Tissue phantoms are widely used for assessing the interaction between the electromagnetic waves and the human body. These are especially key in body area networks, where the body itself acts as the propagation medium since transmission is highly influenced by its diverse dielectric properties. Gels are suitable materials because of their high water content, which is required to mimic the dielectric properties of most tissues. In this paper, PHEA gels are suggested for achieving those properties due to their synthetic nature, which gives them the possibility to be swollen reversibly in more types of mixtures, in addition to water. These gels can be tailored to control the amount of liquid they embed so that they can imitate different body tissues in a wide bandwidth (2¿26.5 GHz), which includes most of the current mobile communication and medical bands. This versatility offers the chance to create heterogeneous models of particular regions of the body, and thus improve the test realism. In addition, they own better mechanical and stability properties than the widely used agar or gelatin.This work was supported in part by the Universitat Politecnica de Valencia-Institut d'Investigacio Sanitaria La Fe (UPV-IIS La Fe) Program [Early Stage Colon Tumour Diagnosis by Electromagnetic Reflection (STuDER), 2016 and Electromagnetic Probe for Early Tumour Detection (EMOTE), 2017], in part by the Universitat Politecnica de Valencia through the Programa de Ayudas de Investigacion y Desarrollo under Grant PAID-01-16, and in part by the European Union's H2020: MSCA: ITN Program for the "mmWave Communications in the Built Environments - WaveComBE" Project under Grant 766231.Castelló-Palacios, S.; Garcia-Pardo, C.; Alloza-Pascual, M.; Fornés Leal, A.; Cardona Marcet, N.; Vallés Lluch, A. (2019). Gel Phantoms for Body Microwave Propagation in the (2 to 26.5) GHz Frequency Band. IEEE Transactions on Antennas and Propagation. 67(10):6564-6573. https://doi.org/10.1109/TAP.2019.2920293S65646573671