Analysis of Wireless Body-Centric Medical Sensors for Remote Healthcare

Aquesta tesi aborda el problema de trobar solucions confortables, de baixa potència i sense fils per aplicacions mèdiques. La tesi tracta els avantatges i les limitacions de tres tecnologies de comunicació diferents per la mesura de paràmetres del cos i mètodes per redissenyar sensors per avaluacions òptimes centrades en el cos. La tecnologia RFID es considera una de les solucions més influents per superar el problema del consum d'energia limitat, a causa de la presència de molts sensors connectats. També s'ha estudiat la tecnologia Bluetooth de baixa energia per resoldre els problemes de seguretat i la distància de lectura que, en general, representen el coll d'ampolla de RFID pels sensors de cos. Els dispositius analògics poden reduir dràsticament les necessitats d'energia a causa dels sensors i les comunicacions, considerant pocs elements i un mètode de transmissió simple. S'estudia un mètode de comunicació completament passiu, basat en FSS, que permet una distància de lectura raonable amb capacitats de detecció precises i confiables, que s'ha discutit en aquesta tesi. L'objectiu d'aquesta tesi és investigar múltiples tecnologies sense fils per dispositius portàtils per identificar solucions adequades per aplicacions particulars en el camp mèdic. El primer objectiu és demostrar la facilitat d'ús de les tecnologies econòmiques sense bateria com un indicador útil de paràmetres fisiopatològics mitjançant la investigació de les propietats de les etiquetes RFID. A més a més, s'ha abordat un aspecte més complex respecte a l'ús de petits components passius com sensors sense fils per trastorns del son. Per últim, un altre objectiu de la tesi és el desenvolupament d'un sistema completament autònom que utilitzi tecnologia BLE per obtenir propietats avançades mantenint baix tant el consum com el preuEsta tesis aborda el problema de encontrar soluciones confortables, inalámbricas y de baja potencia para aplicaciones médicas. La tesis discute las ventajas y limitaciones de tres tecnologías de comunicación diferentes para la medición en el cuerpo y los métodos para elegir y remodelar los sensores para evaluaciones óptimas centradas en el cuerpo. La tecnología RFID se considera una de las soluciones más influyentes para superar el consumo de energía limitado debido a la presencia de muchos sensores conectados. Además, la baja energía de Bluetooth se ha estudiado se ha estudiado la tecnologia Bluetooth de baja energia para resolver los problemas de seguridad y la distancia de lectura que, en general, representan el cuello de botella de la RFID para los sensores de cuerpo. Los dispositivos analógicos pueden reducir drásticamente las necesidades de energía debido a los sensores y las comunicaciones, considerando pocos elementos y un método de transmisión simple. Se estudia un método de comunicación completamente pasivo, basado en FSS, que permite una distancia de lectura razonable con capacidades de detección precisas y confiables, que se ha discutido en esta tesis. El objetivo de esta tesis es investigar múltiples tecnologías inalámbricas para dispositivos portátiles para identificar soluciones adecuadas para aplicaciones particulares en campos médicos. El primer objetivo es demostrar la facilidad de uso de las tecnologías económicas sin batería como un indicador útil de dichos parámetros fisiopatológicos mediante la investigación de las propiedades de las etiquetas RFID. Además, se ha abordado un aspecto más complejo con respecto al uso de pequeños componentes pasivos como sensores inalámbricos para enfermedades del sueño. Por último, un resultado de la tesis es desarrollar un sistema completamente autónomo que utilice la tecnología BLE para obtener propiedades avanzadas que mantengan la baja potencia y un precio bajo.This thesis addresses the problem of comfortable, low powered and, wireless solutions for specific body-worn sensing. The thesis discusses advantages and limitations of three different communication technologies for on body measurement and investigate methods to reshape sensors for optimum body-centric assessments. The RFID technology is considered one of the most influential solutions to overcome the limitated power consumption due to the presence of many sensors connected. Further, the Bluetooth low energy has been studied to solve security problems and reading distance that overall represent the bottleneck of the RFID for the body-worn sensors. Analog devices can drastically reduce the energy needs due to the sensors and the communications, considering few elements and a simple transmitting method. An entirely passive communication method, based on FSS is studied, enabling a reasonable reading distance with precise and reliable sensing capabilities, which has been discussed in this thesis. The objective of this thesis is to investigate multiple wireless technologies for wearable devices to identify suitable solutions for particular applications in medical fields. The first objective is to demonstrate the usability of the inexpensive battery-less technologies as a useful indicator of such a physio-pathological parameters by investigating the properties of the RFID tags. Furthermore, a more complex aspect regards the use of small passive components as wireless sensors for sleep diseases has been addressed. Lastly, an outcome of the thesis is to develop an entirely autonomous system using the BLE technology to obtain advanced properties keeping low power and a low price

Analog Front End for RF Energy Harvesting

This thesis proposes a design for ultra low power sensitive single and dual band RF energy harvesting system for UHF microwave frequencies at 2.4-GHz and 865-MHz to 960- MHz(ISM band). The system is designed to power a load and generate a constant 1-V output voltage for a battery-less passive energy harvesting circuit. Input power is fed from 50 RF source to emulate antenna at UHF microwave band. The design includes single band and dual band off-chip RF matching circuit, RF limiter, Differential Rectifier, Power On Reset (POR), Band Gap Reference (BGR) and Low Drop Out Regulator (LDO). The number of rectifier stages is optimized to obtain a better efficiency to generate 1V output voltage. The full system performance has been verified by simulations for equivalent received power from -20-dBm to -10-dBm. The overall RF energy harvesting system efficiency at -14-dBm (10 m Distance from 4W EIRP source) input power for single band matching at 2.4-GHz is 46.9% with 54Kohm load and for dual band matching at 953-MHz and 2.4-GHz we achieve an efficiency of 41.5% with 61K ohm load and 46% with load 54.4Kohm respectively. The technology node employed is 0.18_m technology. The simulations are carried out at schematic level with bond wire parasitic’s and verified by post layout simulation. At the last we conclude by proposing a novel architecture for constant voltage battery charging

A self-powered single-chip wireless sensor platform

Internet of things” require a large array of low-cost sensor nodes, wireless connectivity, low power operation and system intelligence. On the other hand, wireless biomedical implants demand additional specifications including small form factor, a choice of wireless operating frequencies within the window for minimum tissue loss and bio-compatibility This thesis describes a low power and low-cost internet of things system suitable for implant applications that is implemented in its entirety on a single standard CMOS chip with an area smaller than 0.5 mm2. The chip includes integrated sensors, ultra-low-power transceivers, and additional interface and digital control electronics while it does not require a battery or complex packaging schemes. It is powered through electromagnetic (EM) radiation using its on-chip miniature antenna that also assists with transmit and receive functions. The chip can operate at a short distance (a few centimeters) from an EM source that also serves as its wireless link. Design methodology, system simulation and optimization and early measurement results are presented

Split Ring Resonator Inspired Implantable Platform for Wireless Brain Care

Radio frequency identification (RFID) technology has seen a noticeable tendency in the implementation with biomedical applications. Implantable RFID microelectronic system has been considered as a promising strategy in continuous neural signal extraction to construct the interface between the human brain and computer. This brain-machine interface is believed to largely improve the patients’ potential to recovery from traumatic brain injury or spinal cord injury. The challenge of this approach is the establishment of a reliable wireless data and power link between the implant device and the off-body unit in the high lossy human tissue environment. Meanwhile, the limitation of the implant size also poses another strict requirement to system miniaturization. In this project, a novel split ring resonator (SRR) inspired antenna system comprising a small implantable split ring resonator carrying a UHF RFID microsystem and a wearable split ring is developed and analyzed. The implantable part is self-matched with the RFID IC without additional matching components in the simulated intra-cranial tissue environment. The wearable part concentrically affixed to the scalp is for directivity and radiation efficiency improvement. The physically separated parts of the system form a remotely detectable platform for the wireless brain care applications. In the wireless experiments, the prototyped antenna system is verified to have a backscattered detectable distance of 1.1 m within the entire UHF band from 840 to 960 MHz when the implantable part is submerged 10 mm deep in the human-tissue-like liquid. The detectable distance is also found to have a reverse relationship with the implant depth. With the 5 mm implant depth, the detectable distance reaches a maxi-mum of 1.5 mm at 950 MHz. In order to investigate the system reliability in practical implementation, the detectable distance of the system with lateral and rotational misalignments between the two parts was also measured. The system working distance re-mains higher than 90 cm under marked, up to 5 mm lateral or 45° rotational misalignments between the implantable and wearable parts

Design and Development of Smart Brain-Machine-Brain Interface (SBMIBI) for Deep Brain Stimulation and Other Biomedical Applications

Machine collaboration with the biological body/brain by sending electrical information back and forth is one of the leading research areas in neuro-engineering during the twenty-first century. Hence, Brain-Machine-Brain Interface (BMBI) is a powerful tool for achieving such machine-brain/body collaboration. BMBI generally is a smart device (usually invasive) that can record, store, and analyze neural activities, and generate corresponding responses in the form of electrical pulses to stimulate specific brain regions. The Smart Brain-Machine-Brain-Interface (SBMBI) is a step forward with compared to the traditional BMBI by including smart functions, such as in-electrode local computing capabilities, and availability of cloud connectivity in the system to take the advantage of powerful cloud computation in decision making. In this dissertation work, we designed and developed an innovative form of Smart Brain-Machine-Brain Interface (SBMBI) and studied its feasibility in different biomedical applications. With respect to power management, the SBMBI is a semi-passive platform. The communication module is fully passive—powered by RF harvested energy; whereas, the signal processing core is battery-assisted. The efficiency of the implemented RF energy harvester was measured to be 0.005%. One of potential applications of SBMBI is to configure a Smart Deep-Brain-Stimulator (SDBS) based on the general SBMBI platform. The SDBS consists of brain-implantable smart electrodes and a wireless-connected external controller. The SDBS electrodes operate as completely autonomous electronic implants that are capable of sensing and recording neural activities in real time, performing local processing, and generating arbitrary waveforms for neuro-stimulation. A bidirectional, secure, fully-passive wireless communication backbone was designed and integrated into this smart electrode to maintain contact between the smart electrodes and the controller. The standard EPC-Global protocol has been modified and adopted as the communication protocol in this design. The proposed SDBS, by using a SBMBI platform, was demonstrated and tested through a hardware prototype. Additionally the SBMBI was employed to develop a low-power wireless ECG data acquisition device. This device captures cardiac pulses through a non-invasive magnetic resonance electrode, processes the signal and sends it to the backend computer through the SBMBI interface. Analysis was performed to verify the integrity of received ECG data

On body performance evaluation of passive RFID antennas inside bandage

Radio Frequency Identification (RFID) permits us to remotely exchange information utilizing electromagnetic waves in order to distinguish and track RFID tags by RFID readers. Usually RFID tags contain some code, which is employed for identification purpose. Utilization of RFID's for the detection of objects is becoming more common every day. On the other hand, the field of examining environmental parameters utilizing RFID antennas apparatuses is also evolving number of the environmental parameters are analyzed nowadays utilizing RFID tags, beginning with the identification of a modification of the electric field inside chamber due to change in pressure, to the analysis of change in the body temperature. In this thesis, development and measurement of RFID tags for the measurement of humidity inside bandage are performed. The basic idea of this measurement is to help the doctors in determining the condition of injury inside bandage, as most visible sign for the doctors to determine the condition of injury is humidness inside the bandage. Usually doctors open bandage to check whether the injury is in good condition or not. Detecting humidity level inside the bandage using RFIDs can help doctors to know status of injury without opening bandage, as opening bandage costs time and effort, also opening in unhealthy conditions can cause infection to the injury. Three different kinds of passive RFID tags are used to analyze the performance inside the bandage. One commercial RFID tag known as Dogbone designed by Smartrac is used. This antenna is to measure the humidity level in the industrial environments including construction material, health care, and automotive production units. Dogbone is a UHF RFID antenna, which employs RF Micron IC, innovative product that automatically adjust the input impedance in order to accumulate the changes in the external environment and present results in the digitized output. Although Smartrac´s Dogbone antenna is specially designed for humidity measurement, but because of its high sensitive antenna and weak insulation from the body, its performance dwindles greatly because of body and the bandage. Later on utilizing the brush painting fabrication method for antennas, two type of RFID tags are developed on paper and bandage. Paper utilized for silver brush painting is common A4 paper available for printing purposes while the bandage is made up of Rayon, which is stretchable and commonly used in the first aid kits. Developed antennas are sintered for 15 minutes and 125-degree centigrade, after which their performance is analyzed. Best RFID tags, among all fabricated RFID tags are chosen to do the measurement. Effects of body, bandage and humidity on the performance of RFID tag on paper and bandage RFID tags are analyzed. Smartrac ”Dogbone” and self-designed RFID tags on paper and bandage lose their performance by coming closer to the body, tags loose more performance when they are closer to the inner side of the arm and they are almost least affected by the outer side of arm. Increase in humidity also reduces performance of RFID tags, but interesting phenomenon observed is the effect by the number of turns of the bandage around the RFID tag on the body. The performance of RFID tag fabricated on paper and provided by Smartrac dwindles by increasing turns of the bandage but it’s interesting to note that the tag developed on bandage is almost unaffected by a number of turns of the bandage. Effect of bandage on the RFID tag fabricated on bandage is quite unique, this phenomenon can be utilized in different fields as measurement results show that RFID tag created using same material provide almost same kind of performance under pack-aging of same material but this need further studies to get affirmation

Wireless and Battery-Free Biosignal Monitoring using Passive RFID Tags

Wearable health monitoring devices are becoming increasingly ubiquitous in clinical settings and even in monitoring daily activities. This recent spurt in wearable devices has been made possible through the development of low power electronics, small footprint components and efficient data transmission methods. The next big step in making monitoring devices more 'wearable' is the elimination of batteries. Without the need to replace and recharge batteries, monitoring can be uninterrupted and the monitoring device itself can be seamlessly integrated into garments. However, to achieve this goal, merely reducing sensor power consumption is not enough. There is a need for unconventional methods of health monitoring. par In this work, a novel passive Radio Frequency Identification (RFID) based method for transmitting health parameters wirelessly and without batteries is described. The dissertation proposes an innovative method of transmitting health parameter data by simply turning RFID tags on and off. Technology for RFID based continuous monitoring that include a wireless power harvester and low-power circuits for amplification and health parameter detection are developed in this research. The dissertation includes practical applications of the technology that are demonstrated using heart rate and uterine contraction monitoring as examples. Empirical tests for characterizing the heart rate monitoring system are also conducted. The heart rate monitoring technology is validated with human testing which showed a correlation of over 99% between actual and detected heart rate data.Ph.D., Electrical Engineering -- Drexel University, 201

Self Capacitance based Wireless Power Transfer for Wearable Electronics: Theory and Implementation

Wireless power transfer (WPT

Wireless colorimetric readout to enable resource-limited point-of-care

Patientennahe Diagnostik in Entwicklungsländer birgt spezielle Herausforderungen, die ihren Erfolg bisher begrenzen. Diese Arbeit widmet sich daher der Entwicklung eines in seiner Herstellung skalierbaren und vielseitig einsetzbaren funkbasierten Auslesegerätes für Laborteststreifen. Durch die Kombination einer wachsenden Auswahl an papierbasierten Teststreifendiagnostiken mit gedruckter Elektronik und unter Berücksichtigung des diagnostischen Alltags im südlichen Afrika wurde ein Gerät entwickelt, das Teststreifen zuverlässig ausliest und die Daten per Funk an eine Datenbank übertragen kann. Die Technik basiert auf RFID-Tags (radio frequency identification devices), welche auf verschiedene flexible Substrate gedruckt wurden, um die technische Umsetzbarkeit und Funktionalität zu evaluieren. Um den Preis für die geplante Anwendung niedrig zu halten, wurden unter anderem Papier und Karton als Substrate genutzt. Das Ergebnis dieser Studie sind passive RFID-Tags auf unterschiedlichen, meist günstigen Substraten, die über eine Distanz von über 75 mm betrieben und ausgelesen werden können. Basierend auf der über RFID bereitgestellten Energie und Datenübertragung wurde eine Ausleseeinheit für Standardpapierstreifentests entwickelt und integriert. Durch das Auslesen verschiedener Teststreifen wurde das Gerät evaluiert und in seiner Aussagekraft mit einer scanner-basierten Aufnahme und anschließender Bildanalyse (ImageJ), einem kommerziellen Auslesegerät sowie einer manuellen Auslesung mit Hilfe von Farbtabellen verglichen. Das Gerät kann die Streifen zuverlässig auslesen und die Daten über die RFID-Schnittstelle übertragen. Die funkbasierte Ausleseeinheit ist mit verschiedenen kommerziellen Teststreifen sowohl im biodiagnostischen (lateral flow tests) wie auch im chemischen Bereich (pH-Wert) kompatibel. Die modulare Lösung erlaubt ein breites Einsatzgebiet und führt dadurch zu reduzierten Trainingszeiten der Anwender und einer zuverlässigen Handhabung. Die vorgestellte Lösung ist äußerst kostengünstig und bedarf keiner Wartung, wodurch sie sich sehr gut für den Einsatz in abgelegenen Feldkrankenhäusern eignet. Es wurde ein skalierbarer Prototyp entwickelt, der auf konventionellen Herstellungsverfahren der Verpackungsindustrie aufbaut. Aktuell handelt es sich noch um einen bogenbasierten Prozess, der sich aber prinzipiell auch auf Rolle-zu-Rolle Maschinen übertragen lässt. Bei der Entwicklung des Geräts spielte die Möglichkeit der lokalen Herstellung in den Einsatzländern eine große Rolle. Diese hätte neben der Generierung von Arbeitsplätzen auch den Vorteil einer einfacheren Verteilung der Geräte in ländliche Regionen, in denen sie den größten Nutzen für die Diagnostik erzielen würden

Wireless Power Transfer For Biomedical Applications

In this research wireless power transfer using near-field inductive coupling is studied and investigated. The focus is on delivering power to implantable biomedical devices. The objective of this research is to optimize the size and performance of the implanted wireless biomedical sensors by: (1) proposing a hybrid multiband communication system for implantable devices that combines wireless communication link and power transfer, and (2) optimizing the wireless power delivery system. Wireless data and power links are necessary for many implanted biomedical devices such as biosensors, neural recording and stimulation devices, and drug delivery and monitoring systems. The contributions from this research work are summarized as follows: 1. Development of a combination of inductive power transfer and antenna system. 2. Design and optimization of novel microstrip antenna that may resonate at different ultra-high frequency bands including 415 MHz, 905 MHz, and 1300MHz. These antennas may be used to transfer power through radiation or send/receive data. 3. Design of high-frequency coil (13.56 MHz) to transfer power and optimization of the parameters for best efficiency. 4. Study of the performance of the hybrid antenna/coil system at various depths inside a body tissue model. 5. Minimizing the coupling effect between the coil and the antenna through addressed by optimizing their dimensions. 6. Study of the effects of lateral and angular misalignment on a hybrid compact system consisting of coil and antenna, as well as design and optimize the coilâs geometry which can provide maximum power efficiency under misalignment conditions. 7. Address the effects of receiver bending of a hybrid power transfer and communication system on the communication link budget and the transmitted power. 8. Study the wireless power transfer safety and security systems