Omnidirectional Inductive Powering For Biomedical Implants

Omnidirectional Inductive Powering for Biomedical Implants investigates the feasibility of inductive powering for capsule endoscopy and freely moving systems in general. The main challenge is the random position and orientation of the power receiving system with respect to the emitting magnetic field. Where classic inductive powering assumes a predictable or fixed alignment of the respective coils, the remote system is now free to adopt just any orientation while still maintaining full power capabilities. Before elaborating on different approaches towards omnidirectional powering, the design and optimisation of a general inductive power link is discussed in all its aspects. Special attention is paid to the interaction of the inductive power link with the patient’s body. Putting theory into practice, the implementation of an inductive power link for a capsule endoscope is included in a separate chapter.

Inductive powering has been a reliable and simple method for many years to wirelessly power devices over relatively short distances, from a few centimetres to a few feet. Examples are found in biomedical applications, such as cochlear implants; in RFID, such as smart cards for building access control; and in consumer devices, such as electrical toothbrushes. Device sizes shrunk considerably the past decades, demanding accurate design tools to obtain reliable link operation in demanding environments. With smaller coil sizes, the link efficiency drops dramatically to a point where the commonly used calculation methods become invalid. Inductive Powering: Basic Theory and Application to Biomedical Systems lists all design equations and topology alternatives to successfully build an inductive power and data link for your specific application. It also contains practical guidelines to expand the external driver with a servomechanism that automatically tunes itself to varying coupling and load conditions.

This book offers an up-to-date and comprehensive review of modern antenna systems and their applications in the fields of contemporary wireless systems. It constitutes a useful resource of new material, including stochastic versus ray tracing wireless channel modeling for 5G and V2X applications and implantable devices. Chapters discuss modern metalens antennas in microwaves, terahertz, and optical domain. Moreover, the book presents new material on antenna arrays for 5G massive MIMO beamforming. Finally, it discusses new methods, devices, and technologies to enhance the performance of antenna systems.

For decades, people have searched for ways to harvest energy from natural sources. Lately, a desire to address the issue of global warming and climate change has popularized solar or photovoltaic technology, while piezoelectric technology is being developed to power handheld devices without batteries, and thermoelectric technology is being explored to convert wasted heat, such as in automobile engine combustion, into electricity. Featuring contributions from international researchers in both academics and industry, Energy Harvesting with Functional Materials and Microsystems explains the growing field of energy harvesting from a materials and device perspective, with resulting technologies capable of enabling low-power implantable sensors or a large-scale electrical grid. In addition to the design, implementation, and components of energy-efficient electronics, the book covers current advances in energy-harvesting materials and technology, including: High-efficiency solar technologies with lower cost than existing silicon-based photovoltaics Novel piezoelectric technologies utilizing mechanical energy from vibrations and pressure The ability to harness thermal energy and temperature profiles with thermoelectric materials Whether you’re a practicing engineer, academician, graduate student, or entrepreneur looking to invest in energy-harvesting devices, this book is your complete guide to fundamental materials and applied microsystems for energy harvesting.

Lumbar spinal fusion surgery is performed on patients in whom non-operative treatments have failed to relieve chronic lower back pain (LBP) and restore functionality. The procedure involves inserting titanium alloy rods adjacent to two or more vertebrae on each side of the spine to support spinal fusion. Currently, clinicians rely upon periodic x-ray radiographic images to track fusion progress and determine whether patients can resume normal activities or to assess if the fusion has failed. However, the reliability of imaging evaluation techniques is questionable and leads to either very conservative (and prolonged) restrictions on activity or additional exploratory surgeries. The definitive criteria for a successful fusion remain ambiguous, and determining the progress of spinal fusion remains a challenge for orthopaedic surgeons and clinicians. Observing strain variations on a spinal fusion rod post-implantation has been demonstrated to correlate with changes in bony mass stiffness as fusion progresses, indicating the state of fusion. The challenge with strain measurements relates to having a reliable implant which aligns with existing clinical workflows and provides new data on the state of healing. If the existing titanium alloy rod could be made "smart", i.e. the strain measurement capabilities are embedded into the rod, then the existing clinical, surgical workflow could be maintained. This research focuses on the design and development of a smart spinal fusion implant with the potential to measure strain without complication in the surgical procedure. To meet this aim, two key research questions were addressed. First, a fully implantable wireless spinal rod was developed to support animal trials of spinal fusion. The implant was constructed by mounting a semiconductor strain gauge sensor into a housing machined into a custom spinal rod. A miniaturised electronic module was developed to measure the strain and transmit the data to an external wireless receiver. The module consisted of a strain gauge signal conditioning which was controlled by a microcontroller, and a custom wireless power and data transfer application-specific integrated circuit (ASIC) developed previously at the Auckland Bioengineering Institute (ABI). The electronics module was mounted into the housing, and a printed circuit board (PCB) coil was placed on top of it. This was sealed under a liquid crystal polymer (LCP) lid. Wireless power was transferred to the implant from an external coil at 6.78MHz for 980ms, over which 10 samples of strain were measured. The data was then transmitted using phase-shift keying at a data rate of 678kbps at 6.78MHz. Data was received at an external coil, demodulated and logged to a computer with a measurement cycle taking one second. The implant was characterised on a test rig, and it was confirmed that the 24-bit strain values could be wirelessly measured using the smart spinal implant designed to achieve 1με resolution. This showed that the device was ready for animal trials to quantify strain as fusion occurs in a sheep model. Second, to make the implant clinically relevant, it would be preferable to replace the LCP lid with titanium. LCP is an appropriate seal for animal trials with a lifespan of around several months before water permeates through it, and the device becomes unreliable. Titanium can be welded to the rod to achieve a hermetic seal (gas-tight) with a lifespan of many years, which leads to a smaller device and eases reliable manufacturing as welding is possible. However, this would require transferring inductive power through the conductive titanium lid, which has not been achieved in a spinal implant. Thus, inductive power transfer through metal sheets was investigated via a combination of numerical and experimental tests. A simple test set-up based on hand-wound, cylindrical 10-turn primary (inner radius of 30mm) and 10-turn secondary coils (inner radius of 5mm) was created into which metal sheets could be introduced to allow study their impact on wireless power transfer. The equivalent 2D axisymmetric FEM models were developed to analyse inductive link principles and validate experimental studies. The hand-wound coils were also used to investigate the impact of a titanium enclosure on IWPT system parameters through both simulations and experiments. The simulation results matched experimental results reasonably well, validating the approach; thus, in the future, the validated FEM simulations could be used to investigate power transfer to a miniaturised titanium-packaged smart spinal fusion implant. The impact of the titanium spinal fusion implant, consisting of a titanium spinal rod, housing, and lid, on an IWPT system and an optimum frequency for maximum power transfer was determined. The maximum transferred power was dependent on the titanium alloy, lid thickness, implant size, implant coil location, frequency of power transmission, magnitude of the primary field, and primary and secondary coils dimensions and configurations. FEM simulation results revealed that a maximum power of 1.84mW, at 1A primary current and an operating frequency of approximately 400kHz, could be transferred through a 110μm-thick Grade-5 titanium lid used to seal a 5.5mm-thick, 50mm-long Grade-5 titanium rod, and 0.5m-thick, Grade-5 housing with an internal volume of 18 x 8 x 5mm (L x W x H) for this spinal fusion application. The maximum link potential of 0.035 at 199kHz could be achieved for the same set-up. These results indicated that an acceptable amount of power could be transferred through titanium to power the implanted electronics, supporting the future development of titanium packaged smart spinal fusion rods. This research supports the hypothesis that it is feasible to construct a smart spinal fusion implant that includes the function of measuring strain, can ultimately be employed in clinical practices of spinal fusion, detection of the onset of fusion, non-union or other complications, determination of the efficiency of various bone treatments, and the design of rehabilitation protocols.

Microsystems technologies have found their way into an impressive variety of applications, from mobile phones, computers, and displays to smart grids, electric cars, and space shuttles. This multidisciplinary field of research extends the current capabilities of standard integrated circuits in terms of materials and designs and complements them by creating innovative components and smaller systems that require lower power consumption and display better performance. Novel Advances in Microsystems Technologies and their Applications delves into the state of the art and the applications of microsystems and microelectronics-related technologies. Featuring contributions by academic and industrial researchers from around the world, this book: Examines organic and flexible electronics, from polymer solar cell to flexible interconnects for the co-integration of micro-electromechanical systems (MEMS) with complementary metal oxide semiconductors (CMOS) Discusses imaging and display technologies, including MEMS technology in reflective displays, the fabrication of thin-film transistors on glass substrates, and new techniques to display and quickly transmit high-quality images Explores sensor technologies for sensing electrical currents and temperature, monitoring structural health and critical industrial processes, and more Covers biomedical microsystems, including biosensors, point-of-care devices, neural stimulation and recording, and ultra-low-power biomedical systems Written for researchers, engineers, and graduate students in electrical and biomedical engineering, this book reviews groundbreaking technology, trends, and applications in microelectronics. Its coverage of the latest research serves as a source of inspiration for anyone interested in further developing microsystems technologies and creating new applications.

Sensor technologies and applications are evolving rapidly driven by the demand for new sensors for monitoring and diagnostic purposes to enable improvements in human health and safety. Simultaneously, sensors are required to consume less power, be autonomous, cost less, and be connected by the Internet of Things. New sensor technologies are being developed to fulfill these needs. This book reviews the latest developments in sensor technology and gives the reader an overview of the state-of-the-art in key areas, such as sensors for diagnostics and monitoring. Features Provides an overview of sensor technologies for monitoring and diagnostics applications. Presents state-of-the-art developments in selected topics for sensors that can be used for monitoring and diagnostics in future healthcare, structural monitoring, and smart environment applications. Features contributions from leading international experts in both industry and academia. Explores application areas that include medical diagnostics and screening, health monitoring, smart textiles, and structural monitoring.

A CMOS Self-Powered Front-End Architecture for Subcutaneous Event-Detector Devices presents the conception and prototype realization of a Self-Powered architecture for subcutaneous detector devices. The architecture is designed to work as a true/false (event detector) or threshold level alarm of some substances, ions, etc... that are detected through a three-electrodes amperometric BioSensor approach. The device is envisaged as a Low-Power subcutaneous implantable application powered by an inductive link, one emitter antenna at the external side of the skin and the receiver antenna under the skin. The sensor is controlled with a Potentiostat circuit and then, a post-processing unit detects the desired levels and activates the transmission via a backscattering method by the inductive link. All the instrumentation, except the power module, is implemented in the so called BioChip. Following the idea of the powering link to harvest energy of the magnetic induced link at the implanted device, a Multi-Harvesting Power Chip (MHPC) has been also designed.