Controlling and Processing Core for Wireless Implantable Telemetry System

Wireless implantable telemetry systems are suitable choices for monitoring various physiological parameters such as blood pressure and volume. These systems typically compose of an internal device implanted into a living body captures the physiological data and sends them to an external base station located outside of the body for further processing. The internal device usually consists of a sensor interface to convert the collected data to electrical signals; a digital core to digitize the analog signals, process them and prepare them for transmission; an RF front-end to transmit the data outside the body and to receive the required commands from the end station; and a wireless power supply. The digital core plays an important role in these systems since the data must be digitized and processed before transmitting to the end station for further processing. In this thesis, we presented an FPGA-based prototype for controlling and processing core of a miniature implantable telemetry system that is used to monitoring physiological parameters of laboratory small animals. The presented module samples and digitizes the collected data using an analog to digital converter, stores the collected data, generates the controlling output commands, processing the received data, and controls the power consumption of the system. The circuit is prototyped and experimentally verified using an FPGA development platform, then synthesized and simulated in 130 nm CMOS IC technology using standard digital cells. The overall core design occupies 1.6 mm × 1.6 mm CMOS area, and consumes 14.5 mW (IC) or 208 mW (FPGA) total power

Wireless body sensor networks for health-monitoring applications

This is an author-created, un-copyedited version of an article accepted for publication in Physiological Measurement. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0967-3334/29/11/R01

Doctor of Philosophy

dissertationSince the late 1950s, scientists have been working toward realizing implantable devices that would directly monitor or even control the human body's internal activities. Sophisticated microsystems are used to improve our understanding of internal biological processes in animals and humans. The diversity of biomedical research dictates that microsystems must be developed and customized specifically for each new application. For advanced long-term experiments, a custom designed system-on-chip (SoC) is usually necessary to meet desired specifications. Custom SoCs, however, are often prohibitively expensive, preventing many new ideas from being explored. In this work, we have identified a set of sensors that are frequently used in biomedical research and developed a single-chip integrated microsystem that offers the most commonly used sensor interfaces, high computational power, and which requires minimum external components to operate. Included peripherals can also drive chemical reactions by setting the appropriate voltages or currents across electrodes. The SoC is highly modular and well suited for prototyping in and ex vivo experimental devices. The system runs from a primary or secondary battery that can be recharged via two inductively coupled coils. The SoC includes a 16-bit microprocessor with 32 kB of on chip SRAM. The digital core consumes 350 μW at 10 MHz and is capable of running at frequencies up to 200 MHz. The integrated microsystem has been fabricated in a 65 nm CMOS technology and the silicon has been fully tested. Integrated peripherals include two sigma-delta analog-to-digital converters, two 10-bit digital-to-analog converters, and a sleep mode timer. The system also includes a wireless ultra-wideband (UWB) transmitter. The fullydigital transmitter implementation occupies 68 x 68 μm2 of silicon area, consumes 0.72 μW static power, and achieves an energy efficiency of 19 pJ/pulse at 200 MHz pulse repetition frequency. An investigation of the suitability of the UWB technology for neural recording systems is also presented. Experimental data capturing the UWB signal transmission through an animal head are presented and a statistical model for large-scale signal fading is developed

A Transcutaneous Data and Power Transfer System for Osteogenesis Monitoring Sensors

Implant devices are widely used in health care applications such as life support systems, patient rehabilitation devices and patient monitoring devices. Medical implants have enabled physicians to obtain relevant real time information regarding an organ, or a site of interest with in the body and suggest treatment accordingly. In some cases, the position of the implant within the body or threats of infections prevents wired communication techniques to extract information from the implant. Wireless communication is the alternative in such cases. Distraction osteogenesis is one such application where wireless communication can be established with callus growth monitoring sensors to obtain bone growth data and activate distraction device. As a solution for wireless communication, the computational design, fabrication and testing of a spiral antenna that can operate in the 401-406 MHz Medical Implant Communication Services (MICS) band is detailed. The proposed system uses ZL70103 MICS band transceiver from Microsemi Corporation and enables wireless communication with the implant. Antenna is tested in an in-vivo system that makes use of biomimetic material and pig femur bone to mimic an application environment. Power requirements for the implant actuator system that performs distraction cannot be satisfied by a single battery. Percutaneous wires for powering the implant poses threats of infection and frequent surgeries for battery replacement alters patient’s immune systems. Wireless charging is viable solution in this case. A short range inductive power transfer system prototype is designed and tested on a custom testbed to analyze the power transfer efficiency with change in distance

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

Efficient Universal Computing Architectures for Decoding Neural Activity

The ability to decode neural activity into meaningful control signals for prosthetic devices is critical to the development of clinically useful brain– machine interfaces (BMIs). Such systems require input from tens to hundreds of brain-implanted recording electrodes in order to deliver robust and accurate performance; in serving that primary function they should also minimize power dissipation in order to avoid damaging neural tissue; and they should transmit data wirelessly in order to minimize the risk of infection associated with chronic, transcutaneous implants. Electronic architectures for brain– machine interfaces must therefore minimize size and power consumption, while maximizing the ability to compress data to be transmitted over limited-bandwidth wireless channels. Here we present a system of extremely low computational complexity, designed for real-time decoding of neural signals, and suited for highly scalable implantable systems. Our programmable architecture is an explicit implementation of a universal computing machine emulating the dynamics of a network of integrate-and-fire neurons; it requires no arithmetic operations except for counting, and decodes neural signals using only computationally inexpensive logic operations. The simplicity of this architecture does not compromise its ability to compress raw neural data by factors greater than . We describe a set of decoding algorithms based on this computational architecture, one designed to operate within an implanted system, minimizing its power consumption and data transmission bandwidth; and a complementary set of algorithms for learning, programming the decoder, and postprocessing the decoded output, designed to operate in an external, nonimplanted unit. The implementation of the implantable portion is estimated to require fewer than 5000 operations per second. A proof-of-concept, 32-channel field-programmable gate array (FPGA) implementation of this portion is consequently energy efficient. We validate the performance of our overall system by decoding electrophysiologic data from a behaving rodent.United States. National Institutes of Health (Grant NS056140

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

Design of a Customized multipurpose nano-enabled implantable system for in-vivo theranostics

The first part of this paper reviews the current development and key issues on implantable multi-sensor devices for in vivo theranostics. Afterwards, the authors propose an innovative biomedical multisensory system for in vivo biomarker monitoring that could be suitable for customized theranostics applications. At this point, findings suggest that cross-cutting Key Enabling Technologies (KETs) could improve the overall performance of the system given that the convergence of technologies in nanotechnology, biotechnology, micro&nanoelectronics and advanced materials permit the development of new medical devices of small dimensions, using biocompatible materials, and embedding reliable and targeted biosensors, high speed data communication, and even energy autonomy. Therefore, this article deals with new research and market challenges of implantable sensor devices, from the point of view of the pervasive system, and time-to-market. The remote clinical monitoring approach introduced in this paper could be based on an array of biosensors to extract information from the patient. A key contribution of the authors is that the general architecture introduced in this paper would require minor modifications for the final customized bio-implantable medical device