31 research outputs found

    Millimeter-Scale and Energy-Efficient RF Wireless System

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    This dissertation focuses on energy-efficient RF wireless system with millimeter-scale dimension, expanding the potential use cases of millimeter-scale computing devices. It is challenging to develop RF wireless system in such constrained space. First, millimeter-sized antennae are electrically-small, resulting in low antenna efficiency. Second, their energy source is very limited due to the small battery and/or energy harvester. Third, it is required to eliminate most or all off-chip devices to further reduce system dimension. In this dissertation, these challenges are explored and analyzed, and new methods are proposed to solve them. Three prototype RF systems were implemented for demonstration and verification. The first prototype is a 10 cubic-mm inductive-coupled radio system that can be implanted through a syringe, aimed at healthcare applications with constrained space. The second prototype is a 3x3x3 mm far-field 915MHz radio system with 20-meter NLOS range in indoor environment. The third prototype is a low-power BLE transmitter using 3.5x3.5 mm planar loop antenna, enabling millimeter-scale sensors to connect with ubiquitous IoT BLE-compliant devices. The work presented in this dissertation improves use cases of millimeter-scale computers by presenting new methods for improving energy efficiency of wireless radio system with extremely small dimensions. The impact is significant in the age of IoT when everything will be connected in daily life.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147686/1/yaoshi_1.pd

    A Prospective Look: Key Enabling Technologies, Applications and Open Research Topics in 6G Networks

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    The fifth generation (5G) mobile networks are envisaged to enable a plethora of breakthrough advancements in wireless technologies, providing support of a diverse set of services over a single platform. While the deployment of 5G systems is scaling up globally, it is time to look ahead for beyond 5G systems. This is driven by the emerging societal trends, calling for fully automated systems and intelligent services supported by extended reality and haptics communications. To accommodate the stringent requirements of their prospective applications, which are data-driven and defined by extremely low-latency, ultra-reliable, fast and seamless wireless connectivity, research initiatives are currently focusing on a progressive roadmap towards the sixth generation (6G) networks. In this article, we shed light on some of the major enabling technologies for 6G, which are expected to revolutionize the fundamental architectures of cellular networks and provide multiple homogeneous artificial intelligence-empowered services, including distributed communications, control, computing, sensing, and energy, from its core to its end nodes. Particularly, this paper aims to answer several 6G framework related questions: What are the driving forces for the development of 6G? How will the enabling technologies of 6G differ from those in 5G? What kind of applications and interactions will they support which would not be supported by 5G? We address these questions by presenting a profound study of the 6G vision and outlining five of its disruptive technologies, i.e., terahertz communications, programmable metasurfaces, drone-based communications, backscatter communications and tactile internet, as well as their potential applications. Then, by leveraging the state-of-the-art literature surveyed for each technology, we discuss their requirements, key challenges, and open research problems

    Low-Power High Data-Rate Wireless Transmitter For Medical Implantable Devices

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    RÉSUMÉ Les Ă©metteurs-rĂ©cepteurs radiofrĂ©quences (RF) sont les circuits de communication les plus communs pour Ă©tablir des interfaces home-machine dĂ©diĂ©es aux dispositifs mĂ©dicaux implantables. Par exemple, la surveillance continue de paramĂštres de santĂ© des patients souffrant d'Ă©pilepsie nĂ©cessite un Ă©tage de communication sans-fil capable de garantir un transfert de donnĂ©es rapide, en temps rĂ©el, Ă  faible puissance tout en Ă©tant implĂ©mentĂ© dans un faible volume. La consommation de puissance des dispositifs implantables implique une durĂ©e de vie limitĂ©e de la batterie qui nĂ©cessite alors une chirurgie pour son remplacement, a moins qu’une technique de transfert de puissance sans-fil soit utilisĂ©e pour recharger la batterie ou alimenter l’implant a travers les tissus humains. Dans ce projet, nous avons conçu, implĂ©mentĂ© et testĂ© un Ă©metteur RF Ă  faible puissance et haut-dĂ©bit de donnĂ©es opĂ©rant Ă  902-928 MHz de la bande frĂ©quentielle industrielle-scientifique-mĂ©dicale (ISM) d’AmĂ©rique du Nord. Cet Ă©metteur fait partie d'un systĂšme de communication bidirectionnel dĂ©diĂ© Ă  l’interface sans-fil des dispositifs Ă©lectroniques implantables et mettables et bĂ©nĂ©ficie d’une nouvelle approche de modulation par dĂ©placement de frĂ©quence (FSK). Les diffĂ©rentes Ă©tapes de conception et d’implĂ©mentation de l'architecture proposĂ©e pour l'Ă©metteur sont discutĂ©es et analysĂ©es dans cette thĂšse. Les blocs de circuits sont rĂ©alisĂ©s suivant les Ă©quations dĂ©rivĂ©es de la modulation FSK proposĂ©e et qui mĂšnera Ă  l'amĂ©lioration du dĂ©bit de donnĂ©es et de la consommation d'Ă©nergie. Chaque bloc est implĂ©mentĂ© de maniĂšre Ă  ce que la consommation d'Ă©nergie et la surface de silicium nĂ©cessaires soient rĂ©duites. L’étage de modulation et le circuit mĂ©langeur ne nĂ©cessitent aucun courant continu grĂące Ă  leur structure passive.Parmi les circuits originaux, un oscillateur en quadrature contrĂŽlĂ©-en-tension (QVCO) de faible puissance est rĂ©alisĂ© pour gĂ©nĂ©rer des signaux diffĂ©rentiels en quadrature, rail-Ă -rail avec deux gammes de frĂ©quences principales de 0.3 Ă  11.5 MHz et de 3 Ă  40 MHz. L'Ă©tage de sortie Ă©nergivore est Ă©galement amĂ©liorĂ© et optimisĂ© pour atteindre une efficacitĂ© de puissance de ~ 37%. L'Ă©metteur proposĂ© a Ă©tĂ© implĂ©mentĂ© et fabriquĂ© Ă  la suite de simulations post-layout approfondies.----------ABSTRACT Wireless radio frequency (RF) transceivers are the most common communication front-ends used to realize the human-machine interfaces of medical devices. Continuous monitoring of body behaviour of patients suffering from Epilepsy, for example, requires a wireless communication front-end capable of maintaining a fast, real-time and low-power data communication while implemented in small size. Power budget limitation of the implantable and wearable medical devices obliges engineers to replace or recharge the battery cell through frequent medial surgeries or other power transfer techniques. In this project, a low-power and high data-rate RF transmitter (Tx) operating at North-American Industrial-Scientific-Medical (ISM) frequency band (902-928 MHz) is designed, implemented and tested. This transmitter is a part of a bi-directional transceiver dedicated to the wireless interface of implantable and wearable medical devices and benefits from a new efficient Frequency-Shift Keying (FSK) modulation scheme. Different design and implementation stages of the proposed transmitter architecture are discussed and analyzed in this thesis. The building blocks are realized according to the equations derived from the proposed FSK modulation, which results in improvement in data-rate and power consumption. Each block is implemented such that the power consumption and needed chip area are lowered while the modulation block and the mixer circuit require no DC current due to their passive structure. Among the original blocks, a low-power quadrature voltage-controlled oscillator (QVCO) is achieved to provide differential quadrature rail-to-rail signals with two main frequency ranges of 0.3-11.5 MHz and 3-40 MHz. The power-hungry output stage is also improved and optimized to achieve power efficiency of ~37%. The proposed transmitter was implemented and fabricated following deep characterisation by post-layout simulation. Both simulation and measurement results are discussed and compared with state-of-the-art transmitters showing the contribution of this work in this very popular research field. The Figure-Of-Merit (FOM) was improved, meaning mainly increasing the data-rate and lowering the power consumption of the circuit. The transmitter is implemented using 130 nm CMOS technology with 1.2 V supply voltage. A data-rate of 8 Mb/s was measured while consuming 1.4 mA and resulting in energy consumption of 0.21 nJ/b. The fabricated transmitter has small active silicon area of less than 0.25 mm2

    A prospective look: key enabling technologies, applications and open research topics in 6G networks

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    The fifth generation (5G) mobile networks are envisaged to enable a plethora of breakthrough advancements in wireless technologies, providing support of a diverse set of services over a single platform. While the deployment of 5G systems is scaling up globally, it is time to look ahead for beyond 5G systems. This is mainly driven by the emerging societal trends, calling for fully automated systems and intelligent services supported by extended reality and haptics communications. To accommodate the stringent requirements of their prospective applications, which are data-driven and defined by extremely low-latency, ultra-reliable, fast and seamless wireless connectivity, research initiatives are currently focusing on a progressive roadmap towards the sixth generation (6G) networks, which are expected to bring transformative changes to this premise. In this article, we shed light on some of the major enabling technologies for 6G, which are expected to revolutionize the fundamental architectures of cellular networks and provide multiple homogeneous artificial intelligence-empowered services, including distributed communications, control, computing, sensing, and energy, from its core to its end nodes. In particular, the present paper aims to answer several 6G framework related questions: What are the driving forces for the development of 6G? How will the enabling technologies of 6G differ from those in 5G? What kind of applications and interactions will they support which would not be supported by 5G? We address these questions by presenting a comprehensive study of the 6G vision and outlining seven of its disruptive technologies, i.e., mmWave communications, terahertz communications, optical wireless communications, programmable metasurfaces, drone-based communications, backscatter communications and tactile internet, as well as their potential applications. Then, by leveraging the state-of-the-art literature surveyed for each technology, we discuss the associated requirements, key challenges, and open research problems. These discussions are thereafter used to open up the horizon for future research directions

    Applications of Antenna Technology in Sensors

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    During the past few decades, information technologies have been evolving at a tremendous rate, causing profound changes to our world and to our ways of living. Emerging applications have opened u[ new routes and set new trends for antenna sensors. With the advent of the Internet of Things (IoT), the adaptation of antenna technologies for sensor and sensing applications has become more important. Now, the antennas must be reconfigurable, flexible, low profile, and low-cost, for applications from airborne and vehicles, to machine-to-machine, IoT, 5G, etc. This reprint aims to introduce and treat a series of advanced and emerging topics in the field of antenna sensors

    Antenna Development in Brain-Implantable Biotelemetric Systems for Next-Generation of Human Healthcare

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    In the growing efforts of promoting patients’ life quality through health technology solutions, implantable wireless medical devices (IMDs) have been identified as one of the frontrunners. They are bringing compelling wireless solutions for medical diagnosis and treatment through bio-telemetric systems that deliver real-time transmission of in-body physiological data to an external monitoring/control unit. To set up this bidirectional wireless biomedical communication link for the long- term, the IMDs need small and efficient antennas. Designing antenna-enabled biomedical telemetry is a challenging aim, which must fulfill demanding issues and criteria including miniaturization, appropriate radiation performance, bandwidth enhancement, good impedance matching, and biocompatibility. Overcoming the size restriction mainly depends on the resonant frequency of the required applications. Defined frequency bands for biomedical telemetry systems contain the Medical Implant Communication Service (MICS) operating at the frequency band of 402– 405 MHz, Medical Device Radiocommunication Service (MedRadio) resonating at the frequency ranges of 401– 406 MHz, 413 – 419 MHz, 426 – 432 MHz, 438 – 444 MHz, and 451 – 457 MHz, Wireless Medical Telemetry Service (WMTS) operating at frequency specturms of 1395 to 1400 MHz and 1427 to 1432 MHz, and Industrial, ScientiïŹc, and Medical (ISM) bands of 433.1–434.8 MHz, 868–868.6 MHz, 902.8–928.0 MHz, and 2.4–2.48 GHz. On the other hand, a single band antenna may not fulfill all requirements of a bio-telemetry system in either MedRadio, WMTS, or ISM bands. As a result, analyzing dual/multi-band implantable antenna supporting wireless power, data transmission, and control signaling can meet the demand for multitasking biotelemetry systems. In addition, among different antenna structures, PIFA has been found a promising type in terms of size-performance balance in lossy human tissues. To overcome the above-mentioned challenges, this thesis, first, starts with a discussion of antenna radiation in a lossy medium, the requirements of implantable antenna development, and numerical modeling of the human head tissues. In the following discussion, we concentrate on approaching a new design for far-field small antennas integrated into brain-implantable biotelemetric systems that provide attractive features for versatile functions in modern medical applications. To this end, we introduce three different implantable antenna structures including a compact dual-band PIFA, a miniature triple-band PIFA and a small quad-band PIFA for brain care applications. The compelling performance of the proposed antennas is analyzed and discussed with simulation results and the triple-band PIFA is evaluated using simulation outcomes compared with the measurement results of the fabricated prototype. Finally, the first concept and platform of in-body and off-body units are proposed for wireless dopamine monitoring as a brain care application. In addition to the main focus of this thesis, in the second stage, we focus on introducing an equivalent circuit model to the electrical connector-line transition. We present a data fitting technique for two transmission lines characterization independent of the dielectric properties of the substrate materials at the ultra-high frequency band (UHF). This approach is a promising solution for the development of wearable and off-body antennas employing textile materials in biomedical telemetry systems. The approach method is assessed with measurement results of several fabricated transmission lines on different substrate materials

    Smart Sensor Networks For Sensor-Neural Interface

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    One in every fifty Americans suffers from paralysis, and approximately 23% of paralysis cases are caused by spinal cord injury. To help the spinal cord injured gain functionality of their paralyzed or lost body parts, a sensor-neural-actuator system is commonly used. The system includes: 1) sensor nodes, 2) a central control unit, 3) the neural-computer interface and 4) actuators. This thesis focuses on a sensor-neural interface and presents the research related to circuits for the sensor-neural interface. In Chapter 2, three sensor designs are discussed, including a compressive sampling image sensor, an optical force sensor and a passive scattering force sensor. Chapter 3 discusses the design of the analog front-end circuit for the wireless sensor network system. A low-noise low-power analog front-end circuit in 0.5ÎŒm CMOS technology, a 12-bit 1MS/s successive approximation register (SAR) analog-to-digital converter (ADC) in 0.18ÎŒm CMOS process and a 6-bit asynchronous level-crossing ADC realized in 0.18ÎŒm CMOS process are presented. Chapter 4 shows the design of a low-power impulse-radio ultra-wide-band (IR-UWB) transceiver (TRx) that operates at a data rate of up to 10Mbps, with a power consumption of 4.9pJ/bit transmitted for the transmitter and 1.12nJ/bit received for the receiver. In Chapter 5, a wireless fully event-driven electrogoniometer is presented. The electrogoniometer is implemented using a pair of ultra-wide band (UWB) wireless smart sensor nodes interfacing with low power 3-axis accelerometers. The two smart sensor nodes are configured into a master node and a slave node, respectively. An experimental scenario data analysis shows higher than 90% reduction of the total data throughput using the proposed fully event-driven electrogoniometer to measure joint angle movements when compared with a synchronous Nyquist-rate sampling system. The main contribution of this thesis includes: 1) the sensor designs that emphasize power efficiency and data throughput efficiency; 2) the fully event-driven wireless sensor network system design that minimizes data throughput and optimizes power consumption

    A Wireless, High-Voltage Compliant, and Energy-Efficient Visual Intracortical Microstimulator

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    RÉSUMÉ L’objectif gĂ©nĂ©ral de ce projet de recherche est la conception, la mise en oeuvre et la validation d’une interface sans fil intracorticale implantable en technologie CMOS avancĂ©e pour aider les personnes ayant une dĂ©ficience visuelle. Les dĂ©fis majeurs de cette recherche sont de rĂ©pondre Ă  la conformitĂ© Ă  haute tension nĂ©cessaire Ă  travers l’interface d’électrode-tissu (IET), augmenter la flexibilitĂ© dans la microstimulation et la surveillance multicanale, minimiser le budget de puissance pour un dispositif biomĂ©dical implantable, rĂ©duire la taille de l’implant et amĂ©liorer le taux de transmission sans fil des donnĂ©es. Par consĂ©quent, nous prĂ©sentons dans cette thĂšse un systĂšme de microstimulation intracorticale multi-puce basĂ©e sur une nouvelle architecture pour la transmission des donnĂ©es sans fil et le transfert de l’énergie se servant de couplages inductifs et capacitifs. Une premiĂšre puce, un gĂ©nĂ©rateur de stimuli (SG) Ă©conergĂ©tique, et une autre qui est un amplificateur de haute impĂ©dance se connectant au rĂ©seau de microĂ©lectrodes de l’étage de sortie. Les 4 canaux de gĂ©nĂ©rateurs de stimuli produisent des impulsions rectangulaires, demi-sinus (DS), plateau-sinus (PS) et autres types d’impulsions de courant Ă  haut rendement Ă©nergĂ©tique. Le SG comporte un contrĂŽleur de faible puissance, des convertisseurs numĂ©rique-analogiques (DAC) opĂ©rant en mode courant, gĂ©nĂ©rateurs multi-forme d’ondes et miroirs de courants alimentĂ©s sous 1.2 et 3.3V se servant pour l’interface entre les deux technologies utilisĂ©es. Le courant de stimulation du SG varie entre 2.32 et 220ÎŒA pour chaque canal. La deuxiĂšme puce (pilote de microĂ©lectrodes (MED)), une interface entre le SG et de l’arrangement de microĂ©lectrodes (MEA), fournit quatre niveaux diffĂ©rents de courant avec la valeur maximale de 400ÎŒA par entrĂ©e et 100ÎŒA par canal de sortie simultanĂ©ment pour 8 Ă  16 sites de stimulation Ă  travers les microĂ©lectrodes, connectĂ©s soit en configuration bipolaire ou monopolaire. Cette Ă©tage de sortie est hautement configurable et capable de dĂ©livrer une tension Ă©levĂ©e pour satisfaire les conditions de l’interface Ă  travers l’impĂ©dance de IET par rapport aux systĂšmes prĂ©cĂ©demment rapportĂ©s. Les valeurs nominales de plus grandes tensions d’alimentation sont de ±10V. La sortie de tension mesurĂ©e est conformĂ©ment 10V/phase (anodique ou cathodique) pour les tensions d’alimentation spĂ©cifiĂ©es. L’incrĂ©mentation de tensions d’alimentation Ă  ±13V permet de produire un courant de stimulation de 220ÎŒA par canal de sortie permettant d’élever la tension de sortie jusqu’au 20V par phase. Cet Ă©tage de sortie regroupe un commutateur haute tension pour interfacer une matrice des miroirs de courant (3.3V /20V), un registre Ă  dĂ©calage de 32-bits Ă  entrĂ©e sĂ©rielle, sortie parallĂšle, et un circuit dĂ©diĂ© pour bloquer des Ă©tats interdits.----------ABSTRACT The general objective of this research project is the design, implementation and validation of an implantable wireless intracortical interface in advanced CMOS technology to aid the visually impaired people. The major challenges in this research are to meet the required highvoltage compliance across electrode-tissue interface (ETI), increase lexibility in multichannel microstimulation and monitoring, minimize power budget for an implantable biomedical device, reduce the implant size, and enhance the data rate in wireless transmission. Therefore, we present in this thesis a multi-chip intracortical microstimulation system based on a novel architecture for wireless data and power transmission comprising inductive and capacitive couplings. The first chip is an energy-efficient stimuli generator (SG) and the second one is a highimpedance microelectrode array driver output-stage. The 4-channel stimuli-generator produces rectangular, half-sine (HS), plateau-sine (PS), and other types of energy-efficient current pulse. The SG is featured with low-power controller, current mode source- and sinkdigital- to-analog converters (DACs), multi-waveform generators, and 1.2V/3.3V interface current mirrors. The stimulation current per channel of the SG ranges from 2.32 to 220ÎŒA per channel. The second chip (microelectrode driver (MED)), an interface between the SG and the microelectrode array (MEA), supplies four different current levels with the maximum value of 400ÎŒA per input and 100ÎŒA per output channel. These currents can be delivered simultaneously to 8 to 16 stimulation sites through microelectrodes, connected either in bipolar or monopolar configuration. This output stage is highly-configurable and able to deliver higher compliance voltage across ETI impedance compared to previously reported designs. The nominal values of largest supply voltages are ±10V. The measured output compliance voltage is 10V/phase (anodic or cathodic) for the specified supply voltages. Increment of supply voltages to ±13V allows 220ÎŒA stimulation current per output channel enhancing the output compliance voltage up to 20V per phase. This output-stage is featured with a high-voltage switch-matrix, 3.3V/20V current mirrors, an on-chip 32-bit serial-in parallel-out shift register, and the forbidden state logic building blocks. The SG and MED chips have been designed and fabricated in IBM 0.13ÎŒm CMOS and Teledyne DALSA 0.8ÎŒm 5V/20V CMOS/DMOS technologies with silicon areas occupied by them 1.75 x 1.75mm2 and 4 x 4mm2 respectively. The measured DC power budgets consumed by low-and mid-voltage microchips are 2.56 and 2.1mW consecutively

    1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

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    A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

    Comparative analysis of energy transfer mechanisms for neural implants

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    As neural implant technologies advance rapidly, a nuanced understanding of their powering mechanisms becomes indispensable, especially given the long-term biocompatibility risks like oxidative stress and inflammation, which can be aggravated by recurrent surgeries, including battery replacements. This review delves into a comprehensive analysis, starting with biocompatibility considerations for both energy storage units and transfer methods. The review focuses on four main mechanisms for powering neural implants: Electromagnetic, Acoustic, Optical, and Direct Connection to the Body. Among these, Electromagnetic Methods include techniques such as Near-Field Communication (RF). Acoustic methods using high-frequency ultrasound offer advantages in power transmission efficiency and multi-node interrogation capabilities. Optical methods, although still in early development, show promising energy transmission efficiencies using Near-Infrared (NIR) light while avoiding electromagnetic interference. Direct connections, while efficient, pose substantial safety risks, including infection and micromotion disturbances within neural tissue. The review employs key metrics such as specific absorption rate (SAR) and energy transfer efficiency for a nuanced evaluation of these methods. It also discusses recent innovations like the Sectored-Multi Ring Ultrasonic Transducer (S-MRUT), Stentrode, and Neural Dust. Ultimately, this review aims to help researchers, clinicians, and engineers better understand the challenges of and potentially create new solutions for powering neural implants
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