Keratin peptides from chicken feathers for biomedical applications

Book of Abstracts of CEB Annual Meeting 2017info:eu-repo/semantics/publishedVersio

Extending the limits of wireless power transfer to miniaturized implantable electronic devices

Implantable electronic devices have been evolving at an astonishing pace, due to the development of fabrication techniques and consequent miniaturization, and a higher efficiency of sensors, actuators, processors and packaging. Implantable devices, with sensing, communication, actuation, and wireless power are of high demand, as they pave the way for new applications and therapies. Long-term and reliable powering of such devices has been a challenge since they were first introduced. This paper presents a review of representative state of the art implantable electronic devices, with wireless power capabilities, ranging from inductive coupling to ultrasounds. The different power transmission mechanisms are compared, to show that, without new methodologies, the power that can be safely transmitted to an implant is reaching its limit. Consequently, a new approach, capable of multiplying the available power inside a brain phantom for the same specific absorption rate (SAR) value, is proposed. In this paper, a setup was implemented to quadruple the power available in the implant, without breaking the SAR limits. A brain phantom was used for concept verification, with both simulation and measurement data.This work is supported by FCT with the reference project PTDC/EEI-TEL/5250/2014, by FEDER funds through Projecto 3599-Promover a Produção Científica e Desenvolvimento Tecnológico e a Constituição de Redes Temáticas (3599-PPCDT) and by grant SFRH/BD/116554/2016.info:eu-repo/semantics/publishedVersio

Frequency-spectra-based high coding capacity chipless RFID using an UWB-IR approach

A novel methodology is proposed to reliably predict the resonant characteristics of a multipatch backscatter-based radio frequency identification (RFID) chipless tag. An ultra-wideband impulsion radio (UWB-IR)-based reader interrogates the chipless tag with a UWB pulse, and analyzes the obtained backscatter in the time domain. The RFID system consists of a radar cross-section (RCS)-based chipless tag containing a square microstrip patch antenna array in which the chipless tag is interrogated with a UWB pulse by an UWB-IR-based reader. The main components of the backscattered signal, the structural mode, and the antenna mode were identified and their spectral quality was evaluated. The study revealed that the antenna-mode backscatter includes signal carrying information, while the structural mode backscatter does not include any tag information. The simulation findings were confirmed by experimental measurements obtained in an anechoic chamber environment using a 6-bit multipatch chipless RFID tag. Finally, the novel technique does not use calibration tags and can freely orient tags with respect to the reader.This research work was supported by FCT through grant SFRH/BD/116554/2016 and by the Center for Microelectromechanical Systems Research CMEMS-UMinho

Implantable microdevice with integrated wireless power transfer for thermal neuromodulation applications

Medication resistant neurological and psychiatric disorders, RNPD, are devastating multicausal chronic diseases that cannot be adequately controlled using conventional pharmaco and/or psychotherapies, being epilepsy a well-known RNPD. Wireless biomedical device availability is growing at an impressive rate, and the systems' miniaturization, integration and complexity is also increasing, unveiling new therapies based on such new devices. This paper presents a new wireless implantable device as a solution for thermal neuromodulation of brain cells, which can be used to treat or study the brain's behavior when cooled down. The obtained results show that, despite these systems' potential to be power hungry, they may operate within acceptable electrical power values, while reaching the required neuromodulation temperatures.This work has been supported by FCT (Fundação para a Ciência e Tecnologia) in the scope of the project PTDC/EEITEL/5250/2014, project PTDC/CTM-NAN/5414/2014 and under grant SFRH/BD/100649/2014.info:eu-repo/semantics/publishedVersio

The challenge of long-distance over-the-air wireless links in the ocean: a survey on water-to-water and water-to-land miot communication

Robust wireless communication networks are a cornerstone of the modern world, allowing data to be transferred quickly and reliably. Establishing such a network at sea, a Maritime Internet of Things (MIoT), would enhance services related to safety and security at sea, environmental protection, and research. However, given the remote and harsh nature of the sea, installing robust wireless communication networks with adequate data rates and low cost is a difficult endeavor. This paper reviews recent MIoT systems developed and deployed by researchers and engineers over the past few years. It contains an analysis of short-range and long-range over-the-air radio-frequency wireless communication protocols and the synergy between these two in the pursuit of an MIoT. The goal of this paper is to serve as a go-to guide for engineers and researchers that need to implement a wireless sensor network at sea. The selection criterion for the papers included in this review was that the implemented wireless communication networks were tested in a real-world scenario.cofunded by the project K2D: Knowledge and Data from the Deep to Space with reference POCI-01-0247-FEDER-045941, cofinanced by the European Regional Development Fund (ERDF), through the Operational Program for Competitiveness and Internationalization (COMPETE2020), and by the Portuguese Foundation for Science and Technology (FCT) under the MIT Portugal Program. This work is also cofinanced by national funds through FCT–Fundação para a Ciência e Tecnologia, I.P., under project SONDA (PTDC/EME-SIS/1960/2020). T.M. thanks FCT for grant SFRH/BD/145070/201

Modeling of a compact, implantable, dual-band antenna for biomedical applications

Different implantable antenna designs exist to establish communication with implantable devices depending on the domain of use and the implantation space. Owing to their nature and purposes, these antennas have many imposed criteria on various characteristics, such as bandwidth, multiband behavior, radiation pattern, gain, and specific absorption rate (SAR). This presents a challenge when it comes to achieving satisfying results without a major compromise in any of these crucial parameters. Additionally, many of the existing designs do not follow a specific approach to obtain results. Measuring different parameters of such fabricated structures requires special conditions and special environments mimicking the tissues where they are supposed to be placed. For such issues, the use of biological or synthetic phantoms is widely employed to validate what is obtained in simulation, and a multitude of formulas exist for the creation of such phantoms, each with its advantages and drawbacks. In this paper, a miniature dual-band structure derived from the first iteration of the Koch fractal structure is designed to operate 2 mm below the skin in the arm of the human body, with the MICS (Medical Implant Communication System) and ISM (Industrial, Scientific, Medical) 2.4 GHz bands. The purposes of the design are to derive structures from commonly used shapes with certain behavior while maintaining miniaturization, and to easily design dual-band implantable antennas. More than one band is used to diversify uses, since bands such as the MICS band are mainly dedicated to telemetry. The structure is characterized not only by its low profile compared to various structures found in the literature with dimensions of 17.2 × 14.8 × 0.254 mm3, but also its ease of design, independent shifting of resonant frequencies, and the absence of the need for a matching circuit and a shorting pin (via) for miniaturization. It exhibits satisfying performance: bandwidths of 23 MHz in the MICS band and 190 and 70 MHz in the vicinity of the ISM 2.4 GHz band, and measured gain in the latter band of −18.66 and −17 dBi in the azimuth and elevation radiation patterns, respectively. To validate the antenna’s properties in a skin-mimicking environment, two simple phantom formulas found in the literature were explored and compared in order to identify the best option in terms of accuracy and ease of fabrication.The authors would like to thank Nicolas Corrao for his tremendous effortsthroughout the challenging fabrication process of the preliminary models at the HYPER platform,IMEP-LaHC, University of Grenoble Alpes. R. Silva would like to thank FCT for grant 2021.06819.BD.All individuals included in this section have consented to the acknowledgement

A novel approach for micro-antenna fabrication on ZrO2 substrate assisted by laser printing for smart implants

The use of Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) in medicine has rapidly expanded over the past decade, driven by its advantageous properties, showing potential to overcome titanium alloy in implant fabrication. The release of metal ions and the aesthetic problems of titanium alloy implants are the main reasons for this trend. In addition to meeting expectations regarding its properties, an implant must possess intrinsic capacities such as auto-diagnostic and auto-treatment. Thus, based on the concept of smart implants, this work proposes a hybrid approach for printing a part of the communication system of a zirconia implant by resorting to laser technology, aiming to endow the implant with intrinsic capacities. Therefore, the antenna was designed and then printed on the zirconia surface. The laser was applied as a versatile tool, whether for preparing the surface of the material in a subtractive way, by creating the micro-cavity, or for printing the silver-based antenna in an additive way through laser technology. The silver powder was used as the conductor material of the antenna. The results revealed that the antenna is capable of communicating from inside the body with the outside world without needing to have an exterior antenna attached to the skin.This work has been supported by the FCT (Fundação para a Ciência e Tecnologia -Portugal) in the scope of the projects UID/EEA/04436/2019; Magsense_POCI-01-0247-FEDER-033783, Add.Additive_Manufacturing to Portuguese Industry_POCI-01-0247-FEDER-024533, grant SFRH/BD/ 116554/2016 and the CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for the grant 205791/2014-

Transferência de energia sem fios para dispositivos biomédicos de consumo elevado

Tese de doutoramento em Engenharia BiomédicaAs fontes de energia tradicionais limitam a miniaturização de dispositivos médicos implantáveis, dado que a densidade energética das baterias é insuficiente e o fabrico e integração destas com microssistemas é um desafio. Métodos alternativos para alimentar estes dispositivos são, portanto, muito desejados. Isto permitiria o desenvolvimento de dispositivos mais pequenos, necessários para a criação de novas aplicações que irão revolucionar os cuidados de saúde. À medida que os dispositivos implantáveis ficam mais pequenos, a eficiência da transferência de energia também diminui devido a transdutores e antenas menos eficientes ou ao uso de frequências mais altas que sofrem maior atenuação nos tecidos. Para compensar isto, deve-se aumentar a potência transmitida. Contudo, existem regras de segurança que impõem limites à potência que podemos enviar através do corpo humano. Esta tese aborda as lacunas dos sistemas de transferência de energia sem fios tradicionais através da exploração de parâmetros da ligação que permitam o aumento da energia transferida para o implante sem aumentar os níveis de SAR. Para tal, foi desenvolvido um sistema de transferência de energia sem fios que usa múltiplos transmissores. Através do posicionamento dos transmissores de forma a que os caminhos de propagação de cada um dos seus sinais não se intersetem à superfície do meio, onde o SAR é maior, a energia colocada dentro do meio aumenta enquanto o SAR máximo permanece inalterado. Juntamente com um mecanismo de focagem de energia através da manipulação das fases dos sinais, a distribuição de potência dentro de um fantoma de cabeça humana aumentou drasticamente mantendo o SAR máximo inalterado. O sistema proposto forneceu -13.7 dBm a uma antena colocada a uma profundidade de 5.3 mm num fantoma de cabeça humano. Ajustando a potência transmitida para o SAR10g ser 10 W/kg, a antena receberia -0.9 dBm. Foi também demonstrado que o sistema aumenta até 18 dB e 25 dB a potência entregue a um dispositivo sem fios que circula dentro de modelos de corpo e cabeça humano, respetivamente, comparativamente a um sistema tradicional de uma antena. O sistema de transferência de energia sem fios apresentado nesta tese é escalável, segue o implante enquanto este se move, e concentra energia na sua localização. Adicionalmente, trata o meio como uma caixa negra, não precisando de informação prévia sobre este. Assim sendo, o dispositivo desta tese tem o potencial de contribuir para a forma como se implementam ligações de transferência de energia sem fios para implantes médicos miniaturizados.Conventional power sources remain a major bottleneck in implantable medical device miniaturization, as the achievable energy densities of batteries are insufficient and fabrication and integration with microsystems are still a challenge. Alternative powering methods that can provide energy for the implantable medical device are highly desirable, as the device’s lifetime would no longer be directly correlated to its battery size, allowing the development of smaller devices. This miniaturization of implantable electronic devices is a necessary step to enable new applications that will revolutionise healthcare. Wireless power transfer is an attractive technology to satisfy the power needs of implantable devices. Nevertheless, as implants become smaller, so do their antennas/transducers, causing the efficiency of the power transfer link to decrease, and forcing the use of high frequencies which suffer more attenuation as they propagate through the tissue. To compensate, more power needs to be made available to the implant. However, safety regulations impose a limit to the power transmitted through a human body. This thesis addresses the shortcomings of a traditional wireless power transfer link, by looking into link parameters that can be explored to increase the power delivered to an implant without increasing the maximum SAR value in the medium. To accomplish this, a wireless power transfer system using multiple transmitters was developed. This was achieved by ensuring that the propagation paths of the transmitters’ signals didn’t overlap at the surface of the medium, where SAR is typically higher. Together with the use of a focusing and tracking method through phase control, the power availability inside a human head phantom increased dramatically all over. A power of -13.7 dBm was delivered to an antenna inside a human head phantom at a depth of 5.3 mm. Adjusting the transmitted power for a SAR10g of 10 W/kg, -0.9 dBm would be delivered to the antenna. It was also demonstrated that the proposed system increases the power delivery by up to 18 dB and 25 dB to a wireless device circulating inside human body and head models, respectively, compared to a single transmitter system. The presented wireless power transfer system is scalable, can track the implant as it moves, and focuses the power in its location. Additionally, it doesn’t require information about the medium, treating it as a black box. As such, this thesis’ findings can contribute to shaping how future wireless power transfer links to miniaturized implantable devices are developed.Fundação para a Ciência e Tecnologia (FCT) através da bolsa SFRH/BD/116554/2016, cofinanciada pelo FSE através do Programa Operacional Regional Norte

Avaliação do desempenho de antenas eletricamente pequenas para microdispositivos implantáveis com alimentação e comunicações sem fios

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Eletrónica Médica)Implantable medical electronic devices have a limited lifetime that is often dictated by their batteries’ size and capacity. Energy harvesting and wireless power transfer technologies have the capability to supply power to these devices, making the use of smaller batteries a possibility, which in turn would give birth to new applications requiring smaller devices. The use of radiofrequency to wirelessly transport energy over long distances is an extremely attractive field of investigation, since it is currently used in communication systems and doesn’t pose harm to the human body as long as established exposure limits are not exceeded. An ultra-small antenna is proposed to be used in wireless power transfer (WPT) applications, and its characterization was attempted during this dissertation. Several issues concerning the antenna’s 500 μm dimension had to be faced and overcome, namely antenna handling and the creation of an interface that would allow the antenna to communicate with external instrumentation, such as a virtual network analyzer (VNA). For this purpose, coplanar waveguides (CPW) were designed. Unfortunately, the CPW’s massive size difference comparatively to the antenna caused the first to be better than the latter at radiating energy, as experimentally and numerically verified. To work around this issue, transmission lines with dimensions comparable to those of the antenna were designed and their functionality was tested in a simulation environment. An ultra-small antenna characterization protocol inside an anechoic chamber is proposed in this dissertation, and its feasibility is demonstrated resorting to CPW-based systems, namely a raw CPW, a CPW terminated by a water droplet, a CPW terminated by the ultra-small antenna and a CPW terminated by the antenna surrounded by a water droplet. The use of CPWs and not the small transmission lines was due to the fabrication process of said lines being complex and not yet optimized. HFSS is used in order to validate the antenna characterization protocol, namely by demonstrating that rotating a DUT in relation to a transmission antenna results in a variation of the forward gain, or S21 parameter, that correlates to the rotated DUT’s radiation pattern. The results from the measurement of the four systems’ radiation patterns inside the anechoic chamber further validated the protocol, as measured values presented a resemblance to simulated ones. Even more importantly, experimental results allowed the identification of several interference sources which degraded the obtained radiation patterns, namely reflections of emitted RF signals by transmission cables and support structures, and the evaporation of the water droplet over time, changing its shape and volume, which has been proven to influence an antenna’s behavior. In order to prevent the latter, and at the same time allow measurements to be performed with the antenna surrounded by a human tissue simulant, a phantom with dielectric properties similar to those of the human body has been produced and its stability over 60 minutes has been tested, with its properties remaining unchanged. Currently, there are no validated methods or commercially available instrumentation to perform the characterization of an ultra-small antenna, which puts into perspective the difficulty of the task at hand. Nevertheless, during this dissertation protocols and methods were proposed based on simulations and measurements. Moreover, limitations associated with them have been identified, e.g. the necessity of having ultra-small mounting structures and transmission lines. Solutions to these limitations were also found and proposed, therefore being this work a significant step towards the characterization of ultra-small antennas.Dispositivos médicos implantáveis têm um tempo de vida que é geralmente ditado pelo tamanho e capacidade das suas baterias. Tecnologias de energy harvesting e wireless power transfer têm potencialidade para fornecer energia a estes dispositivos, possibilitando o uso de baterias de mais reduzidas dimensões. O uso de radiofrequências para transportar energia sem fios a longas distâncias é alvo de interesse no mundo da investigação, visto que as radiofrequências são atualmente utilizadas em sistemas de comunicação e não apresentam riscos para o corpo humano, desde que limites de exposição definidos não sejam ultrapassados. Propôs-se a utilização de uma antena ultrapequena em aplicações de wireless power transfer, sendo que durante a presente dissertação tentou-se a sua caracterização. Várias dificuldades associadas à sua dimensão de apenas 500 μm foram enfrentadas e ultrapassadas, nomeadamente o manuseamento da antena e a criação de uma interface que permite a comunicação da antena com instrumentação, como por exemplo um VNA. Para este fim, guias de onda coplanares (CPW) foram projetados. Infelizmente, a grande dimensão do CPW comparativamente à antena faz com que este seja mais eficaz que a antena a radiar energia, o que foi verificado através de simulações e medições. Como resposta a este problema, linhas de transmissão com dimensões equiparáveis às da antena foram projetadas e testadas em simulação. Um protocolo para a caracterização de antenas no interior de câmaras anecoicas foi proposto e a sua aplicabilidade demonstrada recorrendo a sistemas baseados em CPW, nomeadamente um CPW isolado e três CPWs com uma gota de água, uma antena, e uma antena e gota de água, respetivamente, nas terminações. Utilizaram-se os CPW em detrimento das linhas de transmissão pequenas dado que o processo de fabrico destas linhas é complexo e ainda não se encontrava otimizado. Recorreu-se ao HFSS por forma a validar o protocolo de caracterização de antenas que foi proposto, nomeadamente demonstrando que a rotação de um DUT em relação a uma antena emissora resulta numa variação do parâmetro S21 que se relaciona com o diagrama de radiação do DUT rodado. Os resultados das medições dos quatro sistemas baseados em CPW contribuíram para a validação do protocolo, visto que os diagramas medidos apresentaram semelhanças com os simulados. Adicionalmente, as medições realizadas permitiram a identificação de várias fontes de interferências que degradam os diagramas de radiação medidos, nomeadamente reflexões originadas pelos cabos de transmissão e pelos suportes das antenas, e pela evaporação da gota de água que é colocada na terminação de dois dos sistemas, modificando a sua forma e volume, o que se provou afetar o comportamento do sistema. Por forma a evitar isto, e ao mesmo tempo permitir que as medições sejam realizadas com a antena inserida num meio que simula o corpo humano, um fantoma com propriedades elétricas semelhantes às do corpo humano foi produzido e a sua estabilidade ao longo do tempo testada, tendo-se verificado que durante 60 minutos estas não se modificaram. Atualmente, não existem métodos validados ou instrumentos comercializados capazes de realizar a caracterização de uma antena ultrapequena, o que coloca em perspectiva a dificuldade da tarefa a que esta dissertação se propõe. No entanto, protocolos e métodos baseados em simulações e medições foram propostos ao longo desta dissertação. Adicionalmente, as limitações a eles associadas foram identificadas, como por exemplo a necessidade de usar uma estrutura de montagem da antena com dimensões também ultrapequenas. Soluções para estas limitações foram encontradas e propostas, sendo portanto este trabalho um contributo significativo no caminho para a caracterização de antenas ultrapequenas.Fundação para a Ciência e Tecnologia (FCT) - Projeto de investigação PTDC/EEI-TEL/2881/2012Programa Operacional Temático Fatores de Competitividade (COMPETE)Fundo Comunitário Europeu FEDE

A comprehensive review of powering methods used in state-of-the-art miniaturized implantable electronic devices

Microfabrication techniques that allow the integration of all the components in compact and effective volumes, along with the developments observed in sensor and actuator miniaturization, optimization of microelectronic circuits and, ultimately, wireless communication capabilities, have provided the tools required to develop implants for applications so far technically impossible. However, the scaling down of implantable devices raises the problem of how to power them, since batteries have not scaled down as much as the implants. Consequently, energy sources for implantable electronic devices that do not rely on, or at least mitigate, the requirement for a battery are emerging at an astonishing pace. This paper presents a comprehensive review of recent implantable bioelectronic devices that employ alternative powering methods such as energy harvesting and wireless power transfer. A comparison between the different powering methods is provided, along with a discussion of how these may be suited for the device of the future.Work supported by project PTDC/EEI-TEL/29670/2017 - (POCI-01-0145-FEDER-029670), co-financed by the European Regional Development Fund (ERDF), through COMPETE 2020, and by National Agency for Science and Technology (FCT) grant SFRH/BD/116554/2016