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

Design of a Wideband Inductively Coupled Loop Feed Patch Antenna for UHF RFID Tag

A planar wideband patch antenna for ultra-high frequency (UHF) radio frequency identification (RFID) tag for metallic applications is presented in this research work. Three different shape patches are inductively coupled to a triangle loop to form wide impedance bandwidth for universal application UHF (860-960 MHz) RFID. The structure of proposed antenna exhibits planar profile to provide ease of fabrication for cost reduction well suited for mass production. The simulation of the antenna was carried out using Finite Element Method (FEM) based software, Ansoft HFSS v13. The simulated and measured impedance bandwidth of 113 MHz and 117 MHz (Return Loss≥6 dB) were achieved to cover the entire UHF RFID operating frequency band worldwide. The simulated and measured radiation patterns at the operating frequency of 915 MHz are in good agreement. Moreover the simulated minimum antenna gain at the bore sight direction in free space and when mounted on 200 x 200 mm2 metal plate are -15 dBi and -14dBi respectively which is enough to provide reasonable read range over the entire UHF RFID system operating band

Investigation of high bandwith biodevices for transcutaneous wireless telemetry

PhD ThesisBIODEVICE implants for telemetry are increasingly applied today in various areas applications. There are many examples such as; telemedicine, biotelemetry, health care, treatments for chronic diseases, epilepsy and blindness, all of which are using a wireless infrastructure environment. They use microelectronics technology for diagnostics or monitoring signals such as Electroencephalography or Electromyography. Conceptually the biodevices are defined as one of these technologies combined with transcutaneous wireless implant telemetry (TWIT). A wireless inductive coupling link is a common way for transferring the RF power and data, to communicate between a reader and a battery-less implant. Demand for higher data rate for the acquisition data returned from the body is increasing, and requires an efficient modulator to achieve high transfer rate and low power consumption. In such applications, Quadrature Phase Shift Keying (QPSK) modulation has advantages over other schemes, and double the symbol rate with respect to Binary Phase Shift Keying (BPSK) over the same spectrum band. In contrast to analogue modulators for generating QPSK signals, where the circuit complexity and power dissipation are unsuitable for medical purposes, a digital approach has advantages. Eventually a simple design can be achieved by mixing the hardware and software to minimize size and power consumption for implantable telemetry applications. This work proposes a new approach to digital modulator techniques, applied to transcutaneous implantable telemetry applications; inherently increasing the data rate and simplifying the hardware design. A novel design for a QPSK VHDL modulator to convey a high data rate is demonstrated. Essentially, CPLD/FPGA technology is used to generate hardware from VHDL code, and implement the device which performs the modulation. This improves the data transmission rate between the reader and biodevice. This type of modulator provides digital synthesis and the flexibility to reconfigure and upgrade with the two most often languages used being VHDL and Verilog (IEEE Standard) being used as hardware structure description languages. The second objective of this thesis is to improve the wireless coupling power (WCP). An efficient power amplifier was developed and a new algorithm developed for auto-power control design at the reader unit, which monitors the implant device and keeps the device working within the safety regulation power limits (SAR). The proposed system design has also been modeled and simulated with MATLAB/Simulink to validate the modulator and examine the performance of the proposed modulator in relation to its specifications.Higher Education Ministry in Liby

Next generation RFID telemetry design for biomedical implants.

The design and development of a Radio Frequency Identification (RFID) based pressure-sensing system to increase the range of current Intra-Ocular Pressure (IOP) sensing systems is described in this dissertation. A large number of current systems use near-field inductive coupling for the transfer of energy and data, which limits the operational range to only a few centimeters and does not allow for continuous monitoring of pressure. Increasing the powering range of the telemetry system will offer the possibility of continuous monitoring since the reader can be attached to a waist belt or put on a night stand when sleeping. The system developed as part of this research operates at Ultra-High Frequencies (UHF) and makes use of the electromagnetic far field to transfer energy and data, which increases the potential range of operation and allows for the use of smaller antennas. The system uses a novel electrically small antenna (ESA) to receive the incident RF signal. A four stage Schottky circuit rectifies and multiplies the received RF signal and provides DC power to a Colpitts oscillator. The oscillator is connected to a pressure sensor and provides an output signal frequency that is proportional to the change in pressure. The system was fabricated using a mature, inexpensive process. The performance of the system compares well with current state of the art, but uses a smaller antenna and a less expensive fabrication process. The system was able to operate over the desired range of 1 m using a half-wave dipole antenna. It was possible to power the system over a range of at least 6.4 cm when the electrically small antenna was used as the receiving antenna

Design of a Programmable Passive SoC for Biomedical Applications Using RFID ISO 15693/NFC5 Interface

Low power, low cost inductively powered passive biotelemetry system involving fully customized RFID/NFC interface base SoC has gained popularity in the last decades. However, most of the SoCs developed are application specific and lacks either on-chip computational or sensor readout capability. In this paper, we present design details of a programmable passive SoC in compliance with ISO 15693/NFC5 standard for biomedical applications. The integrated system consists of a 32-bit microcontroller, a sensor readout circuit, a 12-bit SAR type ADC, 16 kB RAM, 16 kB ROM and other digital peripherals. The design is implemented in a 0.18 μ m CMOS technology and used a die area of 1.52 mm × 3.24 mm. The simulated maximum power consumption of the analog block is 592 μ W. The number of external components required by the SoC is limited to an external memory device, sensors, antenna and some passive components. The external memory device contains the application specific firmware. Based on the application, the firmware can be modified accordingly. The SoC design is suitable for medical implants to measure physiological parameters like temperature, pressure or ECG. As an application example, the authors have proposed a bioimplant to measure arterial blood pressure for patients suffering from Peripheral Artery Disease (PAD)

Circuits and systems for inductive power transfer

Recently, the development of Wireless Power Transfer (WPT) systems has shown to be a key factor for improving the robustness, usability and autonomy of many mobile devices. The WPT link relaxes the trade-off between the battery size and the power availability, enabling highly innovative applications. This thesis aims to develop novel techniques to increase efficiency and operating distance of inductive power transfer systems. We addressed the design of the inductive link and various circuits used in the receiver. Moreover, we performed a careful system-level analysis, taking into account the design of different blocks and their interaction. The analysis is oriented towards the development of low power applications, such as Active Implantable Medical Device (AIMD) or Radio-Frequency Identification (RFID) systems. Three main approaches were considered to increase efficiency and operating distance: 1) The use of additional resonant coils, placed between the transmitter and the receiver. 2) The receiver coil impedance matching. 3) The design of high-efficiency rectifiers and dc-dc converters. The effect of the additional coils in the inductive link is usually studied without considering its influence on other parts of the WPT system. In this work, we theoretically analyzed and compared 2 and 3-coil links, showing the advantages of using the additional coil together with a matching network in the receiver. The effect of the additional coils in a closed-loop regulated system is also addressed, demonstrating that the feedback-loop design should consider the number of coils used in the link. Furthermore, the inclusion of one additional resonant coil in an actual half-duplex RFID system at 134:2 kHz is presented. The maximum efficiency point can be achieved by adjusting the receiver coil load impedance in order to reach its optimum value. In inductive powering, this optimum impedance is often achieved by adapting the input impedance of a dc-dc converter in the receiver. A matching network can also be used for the same purpose, as have been analyzed in previous works. In this thesis, we propose a joint design using both, matching network and dc-dc converters, highlighting the benefits of using the combined approach. A rectifier must be included in any WPT receiver. Usually, a dc-dc converter is included after the rectifier to adjust the output voltage or control the rectifier load impedance. The efficiency of both, rectifier and dc-dc converter, impacts not only the load power but also the receiver dissipation. In applications such as AIMDs, to get the most amount of power with low dissipation is crucial to full safety requirements. We present the design of an active rectifier and a switched capacitor dc-dc converter. In low-power applications, the power consumption of any auxiliary block used in the circuit may decrease the efficiency due to its quiescent consumption. Therefore, we have carefully designed these auxiliary blocks, such as operational transconductance amplifiers and voltage comparators. The main contributions of this thesis are: . Deduction of simplified equations to compare 2 and 3-coil links with an optimized Matching Network (MN). . Development of a 3-coil link half-duplex RFID 134.2 kHz system. . Analysis of the influence of the titanium case in the inductive link of implantable medical devices. . Development of a joint design ow which exploits the advantages of using both MNs and dc-dc converters in the receiver to achieve load impedance matching. . Analysis of closed-loop postregulated systems, highlighting the effects that the additional coils, receiver resonance (series or parallel), and type of driver (voltage or current) used in the transmitter, have in the feedback control loop. . Proposal of systematic analysis and design of charge recycling switches in step-up dc-dc converters. . New architecture for low-power high slew-rate operational transconductance amplifier. Novel architecture for high-efficiency active rectifier. The thesis is essentially based on the publications [1{9]. During the PhD program, other publications were generated [10{15] that are partially or non-included in the thesis. Additionally, some contributions presented in the text, are in process of publication.Hace ya un buen tiempo que las redes inalámbricas constituyen uno de los temas de investigación más estudiados en el área de las telecomunicaciones. Actualmente un gran porcentaje de los esfuerzos de la comunidad científifica y del sector industrial están concentrados en la definición de los requerimientos y estándares de la quinta generación de redes móviles. 5G implicará la integración y adaptación de varias tecnologías, no solo del campo de las telecomunicaciones sino también de la informática y del análisis de datos, con el objetivo de lograr una red lo suficientemente flexible y escalable como para satisfacer los requerimientos para la enorme variedad de casos de uso implicados en el desarrollo de la “sociedad conectada”. Un problema que se presenta en las redes inalámbricas actuales, que por lo tanto genera un desafío más que interesante para lo que se viene, es la escasez de espectro radioeléctrico para poder asignar bandas a nuevas tecnologías y nuevos servicios. El espectro está sobreasignado a los diferentes servicios de telecomunicaciones existentes y las bandas de uso libre o no licenciadas están cada vez más saturadas de equipos que trabajan en ellas (basta pensar lo que sucede en la banda no licenciada de 2.4 GHz). Sin embargo, existen análisis y mediciones que muestran que en diversas zonas y en diversas escalas de tiempo, el espectro radioeléctrico, si bien está formalmente asignado a algún servicio, no se utiliza plenamente existiendo tiempos durante los cuales ciertas bandas están libres y potencialmente podrían ser usadas. Esto ha llevado a que las Redes Radios Cognitivas, concepto que existe desde hace un tiempo, sean consideradas uno de los pilares para el desarrollo de las redes inalámbricas del futuro. En los ultimos años la transferencia inalámbrica de energía (WPT) ha cobrado especial atención, ya que logra aumentar la robustez, usabilidad y autonomía de los dispositivos móviles. Transferir energía inalámbricamente relaja el compromiso entre el tamaño de la batería y la disponibilidad de energía, permitiendo aplicaciones que de otro modo no serían posibles. Esta tesis tiene como objetivo desarrollar técnicas novedosas para aumentar la eficiencia y la distancia de transmisión de sistemas de transferencia inalámbrica por acople inductivo (IPT). Se abordó el diseño del enlace inductivo y varios circuitos utilizados en el receptor de energía. Además, realizamos un cuidadoso análisis a nivel sistema, teniendo en cuenta el diseño conjunto de diferentes bloques. Todo el trabajo está orientado hacia el desarrollo de aplicaciones de bajo consumo, como dispositivos médicos implantables activos (AIMD) o sistemas de identificación por radio frecuencia (RFID). Se consideraron principalmente tres enfoques para lograr mayor eficienciay distancia: 1) El uso de bobinas resonantes adicionales, colocadas entre el transmisor y el receptor. 2) El uso de redes de adaptación de impedancia en el receptor. 3) El diseño de circuitos rectificdores y conversores dc-dc con alta eficiencia.El efecto ocasionado por las bobinas resonantes adicionales en el enlace inductivo es usualmente abordado sin tener en cuenta su influenciaen todas las partes del sistema. En este trabajo, analizamos teóricamente y comparamos sistemas de 2 y 3 bobinas, mostrando las ventajas que tiene la bobina adicional en conjunto con el uso de redes de adaptación. El efecto de dicha bobina, en sistemas de lazo cerrado fue también estudiado, demostrando que el diseño del lazo debe considerar el número de bobinas que utiliza el link. Se trabajó con un sistema real de RFID, analizando el uso de una bobina resonante en una aplicación práctica existente y de amplio uso en el Uruguay

Near-field baseband communication system for use in biomedical implants

This thesis introduces the reader to the near-field baseband pulse radio communication for biomedical implants. It details the design and implementation of the complete communication system with a particular emphasis on the antenna structure and waveform coding that is compatible with this particular technology. The wireless communication system has great employability in small pill-sized biomedical diagnostic devices offering the advantages of low power consumption and easy integration with SoC and lab-in-a-pill technologies. The greatest challenge was the choice of antenna that had to be made to effectively transmit the pulses. A systematic approach has been carried out in arriving at the most suitable antenna for efficient emanation of pulses and the fields around it are analysed electromagnetically using a commercially available software. A magnetic antenna can be used to transmit the information from inside a human body to the outside world. The performance of the above antenna was evaluated in a salt solution of different concentrations which is similar to a highly conductive lossy medium like a human body. Near-field baseband pulse transmission is a waveform transmission scheme wherein the pulse shape is crucial for decoding information at the receiver. This demands a new approach to the antenna design, both at the transmitter and the receiver. The antenna had to be analysed in the time-domain to know its effects on the pulse and an expression for the antenna bandwidth has been proposed in this thesis. The receiving antenna should be able to detect very short pulses and while doing so has to also maintain the pulse shape with minimal distortion. Different loading congurations were explored to determine the most feasible one for receiving very short pulses. Return-to-zero (RZ), Non-return-zero (NRZ) and Manchester coded pulse waveforms were tested for their compatibility and performance with the near-field baseband pulse radio communication. It was concluded that Manchester coded waveform are perfectly suited for this particular near-field communication technology. Pulse interval modulation was also investigated and the findings suggested that it was easier to implement and had a high throughput rate too. A simple receiver algorithm has been suggested and practically tested on a digital signal processor. There is further scope for research to develop complex signal processing algorithms at the receiver

Energy-Efficient Resource Allocation in Multiuser OFDM Systems with Wireless Information and Power Transfer

In this paper, we study the resource allocation algorithm design for multiuser orthogonal frequency division multiplexing (OFDM) downlink systems with simultaneous wireless information and power transfer. The algorithm design is formulated as a non-convex optimization problem for maximizing the energy efficiency of data transmission (bit/Joule delivered to the users). In particular, the problem formulation takes into account the minimum required system data rate, heterogeneous minimum required power transfers to the users, and the circuit power consumption. Subsequently, by exploiting the method of time-sharing and the properties of nonlinear fractional programming, the considered non-convex optimization problem is solved using an efficient iterative resource allocation algorithm. For each iteration, the optimal power allocation and user selection solution are derived based on Lagrange dual decomposition. Simulation results illustrate that the proposed iterative resource allocation algorithm achieves the maximum energy efficiency of the system and reveal how energy efficiency, system capacity, and wireless power transfer benefit from the presence of multiple users in the system.Comment: 6 pages. The paper has been accepted for publication at the IEEE Wireless Communications and Networking Conference (WCNC) 2013, Shanghai, China, Apr. 201