Wafer-Level Parylene Packaging With Integrated RF Electronics for Wireless Retinal Prostheses

This paper presents an embedded chip integration technology that incorporates silicon housings and flexible Parylene-based microelectromechanical systems (MEMS) devices. Accelerated-lifetime soak testing is performed in saline at elevated temperatures to study the packaging performance of Parylene C thin films. Experimental results show that the silicon chip under test is well protected by Parylene, and the lifetime of Parylenecoated metal at body temperature (37°C) is more than 60 years, indicating that Parylene C is an excellent structural and packaging material for biomedical applications. To demonstrate the proposed packaging technology, a flexible MEMS radio-frequency (RF) coil has been integrated with an RF identification (RFID) circuit die. The coil has an inductance of 16 μH with two layers of metal completely encapsulated in Parylene C, which is microfabricated using a Parylene–metal–Parylene thin-film technology. The chip is a commercially available read-only RFID chip with a typical operating frequency of 125 kHz. The functionality of the embedded chip has been tested using an RFID reader module in both air and saline, demonstrating successful power and data transmission through the MEMS coil

AN INVESTIGATION OF THE POSSIBILITIES OF ROOM-SCALE WIRELESS POWER TRANSFER

Inspired by original work of Nikola Tesla in resonant inductive coupling, numerous investigations are going on making wireless power transfer (WPT) application an optimum choice for various fields. By implementing the concept of non-radiative magnetically-coupled resonant circuits, it has been found that wireless power transmission is achievable at room-scale. This thesis investigates various aspects of the possibilities of room-scale wireless power transfer. Firstly, following the background of WPT systems, MATLAB-coil design, calculation of mutual inductances and Excel-calculation of WPT system performance in multi-resonator systems design tools for WPT systems are discussed for estimating the performance of numerous WPT resonator networks at room-scale. Secondly, the WPT system with two transmitters and a load receiver was simulated for measuring resonator parameters and flux-coupling coefficients between inductors using MATLAB and excel computational tools. Also, the WPT network of four-transmitter coil system was proposed to overcome the shortcomings of two-transmitter coil system xiii incapable of transmitting power efficiently at the various orientation of receiver coil. The goal of this design was to permit greater flexibility in angular position, or attitude of the receiver coil at the room space. The simulated results were found to be promising for room-scale wireless power transmission. The chapter concludes with a design validation that is efficient for a room-scale wireless power transmission. Conclusions and suggestions for future work are provided

A Smart Implantable Bone Fixation Plate Providing Actuation and Load Monitoring for Orthopedic Fracture Healing

Fracture non-union occurs in roughly 5-10% of all fracture cases, and current interventions are both time-consuming and costly. There is therefore significant incentive to develop new tools to improve fracture healing outcomes. Several studies have shown that low-magnitude, high-frequency (LMHF) mechanical loading can promote faster healing and reduce the risk of refracture in critical-size long bone fractures. This is typically done using whole-body vibration, which may result in undesirable systemic effects on the rest of the body. This work discusses an implantable piezoelectric fixation plate that can both apply LMHF loading directly to the fracture site using flexible scheduling and indirectly monitor the progress of healing by using the increasing stiffness of the fracture callus. The design and performance of the piezoelectric bone plate show that the device can apply the target treatment and has the sensitivity to be used to observe the progress of healing. An accompanying telemetry system using BLE communication is also introduced which has a footprint of suitable size to be used in rodent studies and can provide the power necessary for piezoelectric actuation. These results pave the way for future studies regarding the efficacy and optimization of LMHF treatments in fracture healing models

Energy harvesting for marine based sensors

This work examines powering marine based sensors (MBSs) by harvesting energy from their local environment. MBSs intrinsically operate in remote locations, traditionally requiring expensive maintenance expeditions for battery replacement and data download. Nowadays, modern wireless communication allows real-time data access, but adds a significant energy drain, necessitating frequent battery replacement. Harvesting renewable energy to recharge the MBSs battery, introduces the possibility of autonomous MBS operation, reducing maintenance costs and increasing their applicability. The thesis seeks to answer if an unobtrusive energy harvesting device can be incorporated into the MBS deployment to generate 1 Watt of average power. Two candidate renewable energy resources are identified for investigation, ocean waves and the thermal gradient across the air/water interface. Wave energy conversion has drawn considerable research in recent years, due to the large consistent energy flux of ocean waves compared to other conventional energy sources such as solar or wind, but focussing on large scale systems permanently deployed at sites targeted for their favourable wave climates. Although a small amount of research exists on using wave energy for distributed power generation, the device sizes and power outputs of these systems are still one to two orders of magnitude larger than that targeted in this thesis. The present work aims for an unobtrusive device that is easily deployable/retrievable with a mass less than 50kg and which can function at any deployment location regardless of the local wave climate. Additionally, this research differs from previous work, by also seeking to minimise the wave induced pitch motion of the MBS buoy, which negatively affects the data transmission of the MBS due to tilting and misalignment of the RF antenna. Thermal energy harvesting has previously been investigated for terrestrial based sensors, utilising the temperature difference between the soil and ambient air. In this thesis, the temperature difference between the water and ambient air is utilised, to present the first investigation of this thermal energy harvesting concept in the marine environment. A prototype wave energy converter (WEC) was proposed, consisting of a heaving cylindrical buoy with an internal permanent magnet linear generator. A mathematical model of the prototype WEC is derived by coupling a hydrodynamic model for the motion of the buoy with a vibration energy harvester model for the generator. The wave energy resource is assessed, using established mathematical descriptions of ocean wave spectra and by analysing measured wave data from the coast of Queensland, resulting in characteristic wave spectra that are input to the mathematical model of the WEC. The parameters of the WEC system are optimised, to maximise the power output while minimising the pitch motion. A prototype thermal energy harvesting device is proposed, consisting of a thermoelectric device sandwiched between airside and waterside heat exchangers. A mathematical model is derived to assess the power output of the thermal energy harvester using different environmental datasets as input. A physical prototype is built and a number of experiments performed to assess its performance. The results indicate that the prototype WEC should target the high frequency tail of ocean wave spectra, diverging from traditional philosophy of larger scale WECs which target the peak frequency of the input wave spectrum. The analysis showed that the prototype WEC was unable to provide the required power output whilst remaining below 100kg and obeying a 40 degrees pitch angle constraint to ensure robust data transmission. However, a proposed modification to the WECs cylindrical geometry, to improve its hydrodynamic coupling to the input waves, was shown to enable the WEC to provide the required 1W output power whilst obeying the pitch constraints and having a mass below 50kg. The thermal energy harvester results reveal that the thermal gradient across the air/water interface alone is not a suitable energy resource, requiring a device with a cross-sectional area in excess of 100m² to power a MBS. However, including a solar thermal energy collector to increase the airside temperature, greatly improves the performance and enables a thermal energy harvester with a cross-sectional area on the order of 1m² to provide 1W of output power. The findings in this thesis suggest that a well hydrodynamically designed buoy can provide two major benefits for a MBS deployment: enabling efficient wave energy absorption by the MBS buoy, and minimising the wave induced pitch motion which negatively affects the data transmission

Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology

INE/AUTC 10.0

Application of a Design for Excellence Methodology for a Wireless Charger Housing in Underwater Environments

A major effort is put into the production of green energy as a countermeasure to climatic changes and sustainability. Thus, the energy industry is currently betting on offshore wind energy, using wind turbines with fixed and floating platforms. This technology can benefit greatly from interventive autonomous underwater vehicles (AUVs) to assist in the maintenance and control of underwater structures. A wireless charger system can extend the time the AUV remains underwater, by allowing it to charge its batteries through a docking station. The present work details the development process of a housing component for a wireless charging system to be implemented in an AUV, addressed as wireless charger housing (WCH), from the concept stage to the final physical verification and operation stage. The wireless charger system prepared in this research aims to improve the longevity of the vehicle mission, without having to return to the surface, by enabling battery charging at a docking station. This product was designed following a design for excellence (DfX) and modular design philosophy, implementing visual scorecards to measure the success of certain design aspects. For an adequate choice of materials, the Ashby method was implemented. The structural performance of the prototypes was validated via a linear static finite element analysis (FEA). These prototypes were further physically verified in a hyperbaric chamber. Results showed that the application of FEA, together with well-defined design goals, enable the WCH optimisation while ensuring up to 75% power efficiency. This methodology produced a system capable of transmitting energy for underwater robotic applications.This work is funded by the European Commission under the European Union’s Horizon 2020—The EU Framework Programme for Research and Innovation 2014–2020, under grant agreement No. 871571 (ATLANTIS).info:eu-repo/semantics/publishedVersio

Automatic Positioning System for Inductive Wireless Charging Devices and Application to Mobile Robot

Inductive power transfer (IPT) remains one of the most common ways to achieve wireless power transfer (WPT), operating on the same electromagnetic principle as electrical transformers but with an air core. IPT has recently been implemented in wireless charging of consumer products such as smartphones and electric vehicles. However, one major challenge with using IPT remains ensuring precise alignment between the transmitting and receiving coils so that maximum power transfer can take place. In literature, much of the focus is on improving the electrical circuits or IPT coil geometries to allow a greater transmission range. Nevertheless, most IPT products today rely on precise alignment for efficient power transfer. In this thesis, the use of sensing coils to detect and correct lateral misalignments in a typical IPT system is modeled and tested. The sensing coils exploit magnetic-field symmetry to give a nonlinear measure of misalignment direction and magnitude. To test this idea, three experiments are performed: 1) measure the voltage of experimental sensing coils for various lateral misalignment distances, 2) implement closed-loop control and measure performance for an experimental two-dimensional (2D) automatic IPT alignment mechanism, and 3) test automatic IPT alignment on a plausible mobile robot wireless charging scenario. The experimental sensing coils give a misalignment sensing resolution of 1 mm or less in two lateral directions, allowing automatic alignment control in real time with a maximum lateral positioning error of less than √2 mm. This precise alignment allows for efficient power transfer to occur. When implemented on the mobile robot platform, the automatic positioning system gives similar results, allowing the robot to position itself above a wireless charger precisely—a task the mobile robot cannot accomplish using its navigation camera alone. The results of this experiment give confidence that similar sensing coils can be used to reduce lateral misalignments in scaled IPT systems, such as electric-vehicle wireless chargers

Fast contactless vibrating structure characterization using real time field programmable gate array-based digital signal processing: Demonstrations with a passive wireless acoustic delay line probe and vision

International audienceVibrating mechanical structure characterization is demonstrated using contactless techniques best suited for mobile and rotating equipments. Fast measurement rates are achieved using Field Programmable Gate Array (FPGA) devices as real-time digital signal processors. Two kinds of algorithms are implemented on FPGA and experimentally validated in the case of the vibrating tuning fork. A first application concerns in-plane displacement detection by vision with sampling rates above 10 kHz, thus reaching frequency ranges above the audio range. A second demonstration concerns pulsed-RADAR cooperative target phase detection and is applied to radiofrequency acoustic transducers used as passive wireless strain gauges. In this case, the 250 ksamples/s refresh rate achieved is only limited by the acoustic sensor design but not by the detection bandwidth. These realizations illustrate the efficiency, interest, and potentialities of FPGA-based real-time digital signal processing for the contactless interrogation of passive embedded probes with high refresh rates

Printed Spiral Coil Design, Implementation, And Optimization For 13.56 MHz Near-Field Wireless Resistive Analog Passive (WRAP) Sensors

Noroozi, Babak. Ph.D. The University of Memphis. June 2020. Printed Spiral Coil Design, Implementation, and Optimization for 13.56 MHz Near-Field Wireless Resistive Analog Passive (WRAP) Sensors. Major Professor: Dr. Bashir I. Morshed.Monitoring the bio-signals in the regular daily activities for a long time can embrace many benefits for the patients, caregivers, and healthcare system. Early diagnosis of diseases prior to the onset of serious symptoms gives more time to take some preventive action and to begin effective treatment with lower cost. These health and economy benefits are achievable with a user-friendly, low-cost, and unobtrusive wearable sensor that can easily be carried by a patient with no interference with the normal life. The easy application of such sensor brings the smart and connected community (SCC) idea to existence. The spread of a designated disease, like COVID-19, can be studied by collecting the physiological signals transmitted from the wearable sensors in conjunction with a mobile app interface. Moreover, such a comfortable wearable sensor can help to monitor the vital signals during fitness activities for workout concerns. The desire of such wearable sensor has been responded in many researches and commercial products such as smart watch and Fitbit. Wireless connection between the sensor on the body and the scanner is the key and common factor of all convenient wearables. This essential feature has been currently addressed by the costly techniques which is the main impediment to be widely applicable. The existing wireless methods including WiFi, Bluetooth, RFID, and NFC impose cost, complexity, weight, and extra maintenance including battery replacement or recharging, which drove us to propose a low-cost, convenient, and simple technique for wireless connection suitable for battery-less fully-passive sensors. Using a pair of coils connected by the near-field magnetic induction has been copiously used in wireless power transfer (WPT) for medical and industrial applications. However, near field RFID and NFC rely on this technique with active circuits. In contrast, we have proposed a wireless resistive analog passive (WRAP) sensor in which a resistive transducer at the secondary side, affects the primary quality factor (Q) through the inductive connection between a pair of square-shaped Printed Spiral Coils (PSC). The primary 13.56 MHz (ISM band) signal is modulated in response to the continuous change of bio-signal and the amount of response to the unit change in transducer resistance is defined as sensitivity. A higher sensitivity enables the system to respond to the smaller bio-signals and increases the coils maximum relative mobilities. The PSCs specifications and circuit components determine the sensitivity and its tolerance to the coils displacements. We first define and formulize the objective function for coil and components optimization to achieve the maximum sensitivity. Although the optimization methods do not show much different results, due to the speed and simplicity, the Genetic Algorithm (GA) technique is chosen as an advanced method. Then in second optimization stage, the axial and lateral distances that affect the mutual inductance are introduced to the optimization process. The results as a pair of PSCs profiles and the associated circuit components are obtained and fabricated that produced the maximum sensitivity and misalignment tolerance. For the sake of patient comfort, the secondary coil size is fixed at 20 mm and the primary coil is optimized at 60 mm with the maximum (normalized) sensitivity 1.3 m for 16 mm axial distance. If the Read-Zone is defined as the space in which the center of secondary coil can move and the sensitivity keeps at least half of its maximum value, the best Read-Zone has a conical shape with the base radius 22.5 mm and height 14 mm. The analytical results are verified by the measurement results on the fabricated coils and circuits

Optimization of Compensation Network for a Wireless Power Transfer System in Dynamic Conditions: A Circuit Analysis Approach

The paper is focused on the optimization of the compensation network of a wireless power transfer system (WPTS) intended to operate in dynamic conditions. A laboratory prototype of a WPTS has been taken as a reference in this work, allowing for the experimental data and all the numerical models here presented to reproduce the configuration of the existing device. The numerical model has been used to perform FEM analysis with variable relative positions of the emitting and receiving coil to simulate the movement in a 'recharge while driving' condition. Inductive lumped parameters, i.e., self and mutual inductances computed from FEM results, have been used for the optimal design of the compensation network necessary for the WPTS operation. The optimal design of the resonance circuits has been developed by defining objective functions, aiming to achieve these goals: transmitted power must be as constant as possible when the vehicle is in movement and the electrical efficiency must be satisfactory high in most of the coupling conditions. The performances of the optimized network are finally compared and discussed