Preface 1. Wave Theory of Optical Waveguides 2. Planar Optical Waveguides 3. Optical Fibers 4. Couple Mode Theory 5. Nonlinear Optical Effects in Optical Fibers 6. Finite Element Method 7. Beam Propagation Method 8. Staircase Concatention Method 9. Planar Lightwave Circuits 10. Theorems and Formulas Appendix

Fundamentals of optical waveguides

With the miniaturization of personal wearable electronics, considerable effort has been expended to develop high-performance flexible/stretchable energy storage devices for powering integrated active devices. Supercapacitors can fulfill this role owing to their simple structures, high power density, and cyclic stability. Moreover, a high electrochemical performance can be achieved with flexible/stretchable supercapacitors, whose applications can be expanded through the introduction of additional novel functionalities. Here, recent advances in and future prospects for flexible/stretchable supercapacitors with innate functionalities are covered, including biodegradability, self-healing, shape memory, energy harvesting, and electrochromic and temperature tolerance, which can contribute to reducing e-waste, ensuring device integrity and performance, enabling device self-charging following exposure to surrounding stimuli, displaying the charge status, and maintaining the performance under a wide range of temperatures. Finally, the challenges and perspectives of high-performance all-in-one wearable systems with integrated functional supercapacitors for future practical application are discussed.

Flexible/Stretchable Supercapacitors with Novel Functionality for Wearable Electronics.

The technique of wireless power transfer (WPT) via magnetic coupling resonance provides a way to transfer power wirelessly to cardiac pacemakers from external source. For wireless charging system to be used in clinical environment, this paper gives priority consideration to three technical difficulties, i.e., implantation, efficiency, and safety. The LCC-C compensation topology for pacemaker wireless charger is presented, where only one secondary side resonance capacitor needs to be implanted, and resonance compensation parameters are derived. The compensation network can make the WPT system operate at stable resonance and high efficiency. The prototype of the wireless charging system for implantable cardiac pacemaker is developed, where a thin flexible receiving unit was designed to effectively shield eddy currents in the pacemaker shell. The experiments of wireless charging through pork tissues reveal that 3.072-W power can be received from a 3.919-W power source at 300 kHz, reaching a rather high WPT efficiency of 78.4%, such that the charging is fast, i.e., the 1050 mA·h, 4.2-V Li-ion battery voltage increases from 3.98 (80% residual capacity) to 4.2 V within only 27 min, and only 3.3 °C maximum temperature rise of the pork is in safe limits. The feasibility and safety of the charging system were further evaluated by simulations of specific absorption rate and temperature rise in human tissues and electromagnetic fields in the pacemaker case.

An LCC-C Compensated Wireless Charging System for Implantable Cardiac Pacemakers: Theory, Experiment, and Safety Evaluation

The development of MRI systems operating at or above 7 T has provided researchers with a new window into the human body, yielding improved imaging speed, resolution and signal-to-noise ratio. In order to fully realise the potential of ultrahigh-field MRI, a range of technical hurdles must be overcome. The non-uniformity of the transmit field is one of such issues, as it leads to non-uniform images with spatially varying contrast. Parallel transmission (i.e. the use of multiple independent transmission channels) provides previously unavailable degrees of freedom that allow full spatial and temporal control of the radiofrequency (RF) fields. This review discusses the many ways in which these degrees of freedom can be used, ranging from making more uniform transmit fields to the design of subject-tailored RF pulses for both uniform excitation and spatial selection, and also the control of the specific absorption rate. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/nbm.3313

Parallel transmission for ultrahigh‐field imaging

With a consumer and / or energy storage device, from the or the mobile moving body 3 moving on or roadway or rail is stopped, apparatus for inducing transmitting electrical energy, the roadway 1 comprising a floor derivative 5 which is attached, this floor derivative with a number of first induction coil 4 connected to the arranged and power along the roadway 1 or rail, the first induction coil towards the mobile 3 It has a magnetic conductive iron core 6 to generate a magnetic field oriented in. Inductive wheel 8 attached to the movable body 3 is magnetically conductive core 10 and the second induction coil 9 fixed with a magnetically conductive wheel disc 11 facing towards the linked roadway 1 or rails on both sides of the core , and a 12. To ensure low reluctance loss between and induction coil 4, 9 for contacting the road 1, the magnetic conductivity of the tire 13 is attached to the wheel disc by an elastic which is rotated by the movement of the object 3, the tire flat in the pressed state, to reliably bridge the gap remaining between the roadway and wheel disc. This device is advantageously used in conjunction with an electric vehicle in order to comfortably and quickly recharge the battery during or in parked cars.

Apparatus for transmitting electrical energy

This paper presents a multiband conformal antenna for implantable as well as ingestible devices. The proposed antenna has the following three bands: medical implanted communication service (MICS: 402–405 MHz), the midfield band (1.45–1.6 GHz), and the industrial, scientific, and medical band (ISM: 2.4–2.45 GHz) for telemetry or wireless monitoring, wireless power transfer (WPT), and power conservation, respectively. A T-shaped ground slot is used to tune the antenna, and this antenna is wrapped inside a printed 3-D capsule prototype to demonstrate its applicability in different biomedical devices. Initially, the performance of the proposed antenna was measured in an American Society for Testing and Materials phantom containing a porcine heart in the MICS band for an implantable case. Furthermore, to stretch the scope of the suggested antenna to ingestible devices, the antenna performance was simulated and measured using a minced pork muscle in the ISM band. A modified version of the midfield power transfer method was incorporated to replicate the idea of WPT within the implantable 3-D printed capsule. Moreover, a near-field plate (NFP) was employed to control the leakage of power from the WPT transmitter. From the simulation and measurements, we found that use of a ground slot in the implantable antenna can improve antenna performance and can also reduce the specific absorption rate. Furthermore, by including the NFP with the midfield WPT transmitter system, unidirectional wireless power can be obtained and WPT efficiency can be increased.

A Multiband Antenna Associating Wireless Monitoring and Nonleaky Wireless Power Transfer System for Biomedical Implants

In this paper, a conformal wideband circularly polarized (CP) antenna is presented for endoscopic capsule application over the 915-MHz Industrial, Scientific, and Medical (902–928 MHz) band. The thickness of the antenna is only 0.2 mm, which can be wrapped inside a capsule’s inner wall. By cutting meandered slots on the patch, using open-end slots on the ground, and utilizing two long arms, the proposed antenna obtains a significant size reduction. In the conformal form, the antenna volume measures only 66.7 mm3. A single-layer homogeneous muscle phantom box is used for the initial design and optimization with parametric studies. The effect of the internal components inside a capsule is discussed in analyzing the antenna’s performance and to realize a more practical scenario. In addition, a realistic human body model in a Remcom XFdtd simulation environment is considered to evaluate the antenna characteristics and CP purity, and to specify the specific absorption rate limit in different organs along the gastrointestinal tract. The performance of the proposed antenna is experimentally validated by using a minced pork muscle phantom and by using an American Society for Testing and Materials phantom immersed in a liquid solution. For measurements, a new technique applying a printed 3-D capsule is devised. From simulations and measurements, we found that the impedance bandwidth of the proposed antenna is more than 20% and with a maximum simulated axial ratio bandwidth of around 29.2% in homogeneous tissue. Finally, a wireless communication link at a data rate of 78 Mb/s is calculated by employing link-budget analysis.

A Wideband Circularly Polarized Conformal Endoscopic Antenna System for High-Speed Data Transfer

This communication proposes miniaturized implantable antenna systems for biomedical applications, specifically for scalp implantation. The proposed designs exhibit dual-band characteristics on the industrial, scientific, and medical bands (i.e., 915 and 2450 MHz) with small volumes: 344 mm3 (System A) and 406 mm3 (System B). Each system is integrated with the microelectronic components and a battery. The key feature of the proposed implantable antenna is its small volume ( $8 \times 6 \times 0.5$ = 24 mm3) with a slotless and a vialess ground plane, thereby reducing design complexity. Moreover, the structure exhibits satisfactory peak gain values of −28.5 and −22.8 dBi at a lower and higher resonant band, respectively. Simulations using the finite-element method and finite-difference time domain are performed to evaluate the implantable systems. For validation, measurements are carried out in a saline solution. The antenna offers a good agreement between the measured and simulation results. In addition, a link budget is calculated to analyze the data transmission range.

Scalp-Implantable Antenna Systems for Intracranial Pressure Monitoring

This communication presents a miniaturized triple band implantable antenna system for multiple biotelemetry applications, which operates at the industrial, scientific, and medical (ISM) band (902–928 MHz and 2400–2483.5 MHz) and the midfield band (1824–1980 MHz). These bands are intended for the function of data telemetry, wireless power transfer, and power saving. The recommended antenna system is comprised of two implantable devices, a capsule type for deep tissue implantation and a flat type for skin implantation. The volume of these devices is 647 mm3 and 425.6 mm3, respectively. The compact size of the proposed antenna system is 21 mm3 ( $7\,\,\text {mm} \times 6 \,\,\text {mm} \times 0.5$ mm), which is the smallest size yet presented. The miniaturization is achieved by meandering the shape of the radiating patch, adding an open-end ground slot, and introducing a shorting pin between ground plane and radiating patch. In the proposed antenna, simulated bandwidth is 8.7% and 7.3% at the ISM bands and 8.2% at the midfield band, and the measured bandwidth in a saline solution is 14.7% and 24.8% at the ISM bands and 13.1% at the midfield band. Finally, a link budget is calculated at different data rates to specify a range for data telemetry.

A Miniaturized Triple-Band Implantable Antenna System for Bio-Telemetry Applications

In this letter, two skin-implantable biotelemetry devices are presented along with an antenna system that operates on five bands, including the Medical Implant Communication Service (MICS) (402–405 MHz) and the Industrial, Scientific, and Medical (ISM) (433.1–434.8 MHz, 868.0–868.6 MHz, 902–928 MHz, 2400.0–2483.5 MHz) bands. A link budget analysis was used to configure an algorithm for effective device operation. These devices contain space for storage batteries, controlling electronics, and bio-sensors, along with a planar inverted-F antenna (PIFA), and have total volume of 617 and 510 ${\text{mm}}^{3}$ respectively. These devices were primarily designed and simulated in different environments with FDTD software. In addition, the performance of the antenna system was evaluated from measurements made inside a skin-mimicking semi-solid homogeneous phantom. This research shows that multi-channel communication will enhance the diversity of biotelemetry devices.

Hyoungsuk Yoo

Papers

A Multiband Antenna Associating Wireless Monitoring and Nonleaky Wireless Power Transfer System for Biomedical Implants

A Wideband Circularly Polarized Conformal Endoscopic Antenna System for High-Speed Data Transfer

Scalp-Implantable Antenna Systems for Intracranial Pressure Monitoring

A Miniaturized Triple-Band Implantable Antenna System for Bio-Telemetry Applications

Multi-Band Antenna System for Skin Implant