Capacitive Coupling Research Articles

96‐3: Invited Paper: Next‐Gen Interactions: Creative Sensing Solutions for Automotive Capacitive Knobs on Displays

Automakers are adding back mechanical knobs to modern car cabins to address concerns about the difficulty of adjusting vehicle setting controls through the touchscreen interface. Passive capacitive knobs attached to touchscreens are a great solution as they provide a seamless interface while using the same capacitive sensors that sense finger touches. Existing knobs rely on capacitive coupling to a user's hand, making it difficult to support gloved hands. The proposed knob resolves this by employing a unique sensing architecture while providing additional features such as initial state detection and fall‐off detection.

Don’t Touch the Bed! Capacitive Coupling in Electrosurgery Causes Current Loss During Pinch Burning

Don’t Touch the Bed! Capacitive Coupling in Electrosurgery Causes Current Loss During Pinch Burning

Demonstration of an energy-efficient Ising solver composed of Ovonic threshold switch (OTS)-based nano-oscillators (OTSNOs)

As there is an increasing need for an efficient solver of combinatorial optimization problems, much interest is paid to the Ising machine, which is a novel physics-driven computing system composed of coupled oscillators mimicking the dynamics of the system of coupled electronic spins. In this work, we propose an energy-efficient nano-oscillator, called OTSNO, which is composed of an Ovonic Threshold Switch (OTS) and an electrical resistor. We demonstrate that the OTSNO shows the synchronization behavior, an essential property for the realization of an Ising machine. Furthermore, we have discovered that the capacitive coupling is advantageous over the resistive coupling for the hardware implementation of an Ising solver by providing a larger margin of the variations of components. Finally, we implement an Ising machine composed of capacitively-coupled OTSNOs to demonstrate that the solution to a 14-node MaxCut problem can be obtained in 40 µs while consuming no more than 2.3 µJ of energy. Compared to a previous hardware implementation of the phase-transition nano-oscillator (PTNO)-based Ising machine, the OTSNO-based Ising machine in this work shows the performance of the increased speed by more than one order while consuming less energy by about an order.

Experiment of electrothermal stress for different types of end turn grading in the inverter‐fed form‐wound windings

AbstractEnd turn grading with resistive–capacitive coupling experiences severe electrothermal stress when subjected to pulse width modulation (PWM) voltage. In this paper, several experiments and simulations were carried conducted for four types of end turn grading. First of all, the temperature rise in the end turn grading increased with a decrease in rise time. When the rise time was less than 500 ns, the temperature rise at the terminal was higher owing to the increased capacitive current coupled from the main wall insulation. Further, the current in the linear region exhibited minimal variation at different fundamental frequencies resulting in synchronized the temperature rise at the terminal and overlap. Furthermore, the jump voltage was the key factor influencing temperature rise in end turn grading, confirmed by comparing different voltage magnitudes. Finally, the transient behaviour of the maximum field in the stress grading material was determined at rise time. The experimental and simulation results indicate that balancing and interdependently addressing the electrical and thermal stress protection in end turn grading is crucial. The study aims to provide an experimental and theoretical foundation for an insulation system of inverter‐fed rotating machinery operating under PWM voltage.

A CMOS Rectifier with a Wide Dynamic Range Using Switchable Self-Bias Polarity for a Radio Frequency Harvester

This paper presents a switchable self-bias polarity on the CMOS complementary cross-coupled rectifier to improve the rectifier’s power conversion efficiency (PCE) profile across a wide input power (PIN) dynamic range. This technique achieves this by adaptively switching the polarity of the bias on the n-MOS to overdrive it during low PIN to improve the sensitivity and underdrive it during high PIN to suppress the shoot-through loss and the unnecessary discharge of the coupling capacitor. The popular self-biased p-MOS is also implemented further to reduce the reverse conduction loss during high PIN. The proposed rectifier is fabricated in a 40 nm CMOS process and operates at 900 MHz with a load of 50 kΩ. The proposed rectifier achieved a peak PCE of 72.1% and maintained a 0.8xPCEPEAK across a PIN dynamic range of 11.5 dB.

Superionic fluoride gate dielectrics with low diffusion barrier for two-dimensional electronics.

Exploration of new dielectrics with a large capacitive coupling is an essential topic in modern electronics when conventional dielectrics suffer from the leakage issue near the breakdown limit. Here, to address this looming challenge, we demonstrate that rare-earth metal fluorides with extremely low ion migration barriers can generally exhibit an excellent capacitive coupling over 20 μF cm-2 (with an equivalent oxide thickness of ~0.15 nm and a large effective dielectric constant near 30) and great compatibility with scalable device manufacturing processes. Such a static dielectric capability of superionic fluorides is exemplified by MoS2 transistors exhibiting high on/off current ratios over 108, ultralow subthreshold swing of 65 mV dec-1 and ultralow leakage current density of ~10-6 A cm-2. Therefore, the fluoride-gated logic inverters can achieve notably higher static voltage gain values (surpassing ~167) compared with a conventional dielectric. Furthermore, the application of fluoride gating enables the demonstration of NAND, NOR, AND and OR logic circuits with low static energy consumption. In particular, the superconductor-insulator transition at the clean-limit Bi2Sr2CaCu2O8+δ can also be realized through fluoride gating. Our findings highlight fluoride dielectrics as a pioneering platform for advanced electronic applications and for tailoring emergent electronic states in condensed matter.

From interface effect to bulk effect: Probing the capacitive coupling enhancement mechanism to achieve high performance DC droplet-based nanogenerator

The DC droplet-based nanogenerator (DNG) technology has opened up a new avenue for high-entropy water energy harvesting. However, the conventional DC DNG relies on the interface effect to generate a limited surface charge density, which severely restricts its electrical performance. Here, inspired by the MOS transistors, a novel total current DNG (TC-DNG) platform with back-gate modulation structure is developed, successfully realizing the transform from interface effect to bulk effect. By using the rationally patterned DNG as triboelectric probe, an intriguing capacitive coupling enhancement mechanism is discovered. With such a mechanism, the nanogenerator could employ both the capacitive coupling effect of the back-gate electrode and the self-exciting effect of droplet charge-shuttles to achieve a significantly enhanced performance in both charge transfer and voltage output. As a result, this TC-DNG provides a transferred charge of 30 nC per droplet and an output voltage of 800 V and is capable of illuminating 480 high-brightness LEDs without using any power management circuit. In addition, this TC-DNG could easily adapt to a wide range of application scenarios owing to the interchangeability of the back-gate material. This work could inspire further innovations in energy transfer mechanism and harvesting technology at the liquid-solid interface.

Conceptual design of a high reactive-power ferroelectric fast reactive tuner

We present a novel design of a ferroelectric fast reactive tuner (FE-FRT) capable of modulating mega-VAR reactive power on a submicrosecond timescale. The high reactive power capability of our design extends the range of applications of reactive tuners to numerous applications. We present a detailed analytical model of the performance of a megawatt-class reactive power device and benchmark it against finite-element method eigenmode and frequency domain electromagnetic simulations. We introduce new features, including an annulus design for the ferroelectric capacitors and capacitive window coupling to the cavity. We consider thermal design issues and nonlinear effects in the ferroelectric. The model covers several configurations, allowing control of the frequency of superconducting and normal-conducting cavities in a variety of applications and frequencies. We calculate that the FE-FRT designed should be capable of handling around 0.45 MVAR of reactive power with around 3 kW of resistive losses, providing a frequency tuning range of 8 kHz in an example of 400 MHz cavity geometry. Published by the American Physical Society 2024

Study of Acoustic Emission from the Gate of Gallium Nitride High Electron Mobility Transistors

Nitrides are the leading semiconductor material used for the fabrication of high electron mobility transistors (HEMTs). They exhibit piezoelectric properties, which, coupled with their high mechanical stiffness, expand their versatile applications into the fabrication of piezoelectric devices. Today, due to advances in device technology that result in a reduction in the size of individual transistor elements and due to increased structural complexity (e.g., multi-gate transistors), the integration of piezoelectric materials into HEMTs leads to an interesting occurrence, namely acoustic emission from the transistor gate due to piezoelectric effects. This could affect the device’s performance, reliability, and durability. However, this phenomenon has not yet been comprehensively described. This paper aims to examine this overlooked aspect of AlGaN/GaN HEMT operation, that is, the acoustic emission from the gate region of the device induced by piezoelectric effects. For this purpose, dedicated test structures were designed, consisting of two narrow 1.7 μm-wide metallization strips placed at distances ranging from 5 μm to 200 μm fabricated in AlGaN/GaN heterostructures to simulate and examine the gate behavior of the HEMT transistor. For comparison, the test device structures were also fabricated on sapphire, which is not a piezoelectric material. Measurements of acoustic and electrical interactions in the microwave range were carried out using the “on wafer” method with Picoprobe’s signal–ground–signal (SGS)-type microwave probes. The dependence of reflectance |S11| and transmittance |S21| vs. frequency was investigated, and the coupling capacitance was determined. An equivalent circuit model of the test structure was developed, and finite element method simulation was performed to study the distribution of the acoustic wave in the nitride layers and substrate for different frequencies using Comsol Multiphysics software. At frequencies up to 2–3 GHz, the formation of volume waves and a surface wave, capable of propagating over long distances (in the order of tens of micrometers) was observed. At higher frequencies, the resulting distribution of displacements as a result of numerous reflections and interferences was more complicated. However, there was always the possibility of a surface wave occurrence, even at large distances from the excitation source. At small gate distances, electrical interactions dominate. Above 100 µm, electrical interactions are comparable to acoustic ones. With further increases in distance, weakly attenuated surface waves will dominate.

Active Fault-Locating Scheme for Hybrid Distribution Line Based on Mutation of Aerial-Mode Injected Pulse

Due to the overlap of initial traveling wave signals, the traveling wave propagation process in hybrid distribution lines is complicated to analyze. The most significant challenge posed by the traditional passive traveling wave-locating method for hybrid distribution lines lies in identifying the fault section and distinguishing the reflected wave from the fault point or the hybrid connection points. Based on this approach, with the application of the aerial-mode component of the pulse signal generated at the fault point, a fault-section-identification and fault-locating scheme for hybrid distribution feeders with active pulse injection is proposed. When power in a line is cut after a single-to-line ground (SLG) fault occurs, the same pulse is injected into the three phases from the neutral point of the coupling capacitor bank to construct the zero-mode component, which propagates to the SLG fault three-phase asymmetrical point, producing an aerial-mode component that is reflected back to the first end of the line. With the application of the arrival time of an aerial-mode wavefront, it is simple to locate the SLG fault for arbitrary forms of hybrid lines. The simulation results confirm the feasibility of the fault-locating scheme under different feeders, different fault locations, and fault resistances. The results of the experiments confirm the high practical value of the proposed method.

A robust parity‐time‐symmetric hybrid wireless power transfer system with extended coupling range

SummaryInductive power transmission (IPT) and capacitive power transmission (CPT) are currently the two main wireless power transfer technologies. Hybrid power transmission (HPT) systems that combine IPT and CPT can improve transmission performance and are more attractive for some charging applications such as electric bicycles (e‐bikes). However, HPT systems are more sensitive to parameter variations, and the coupling mechanism is prone to misalignment during wireless charging. Therefore, achieving stable output power and constant transfer efficiency over a wide range of coupling coefficient variations is still a major challenge for HPT systems. In this work, the parity–time (PT) symmetry theory is applied to an SS‐type HPT system, and a circuit model of the PT‐based HPT system is developed by using coupling capacitance and coupling inductance. The effect of connecting the plates to the homonymous end or heteronymous end of the coupling coils on the PT symmetry range of the HPT system is discussed. It is found that the heteronymous end connection of the coils can effectively increase the range of constant output power and stable transfer efficiency. Finally, a prototype is built to verify the feasibility and effectiveness of the proposed PT‐based HPT system. The transfer power and efficiency remain constant in the PT‐symmetric range, and the inductive and capacitive coupling coefficients are smaller compared to IPT and CPT systems with the same parameters.

Tackling capacitive coupling in broad-band spectral electrical impedance tomography (sEIT) measurements by selecting electrode configurations

SUMMARY Electromagnetic (EM) coupling effects including both inductive and capacitive coupling have long been an essential problem in broad-band spectral electrical impedance tomography (sEIT) measurements at the field scale. Efforts have been made to remove EM coupling numerically or to suppress the effects by modified data acquisition strategies. For near-surface applications with relatively small survey layouts, inductive coupling can be well removed in the mHz to kHz frequency range. With the use of shielded coaxial cables and so-called active electrodes where the amplifiers are mounted at the electrodes, capacitive coupling in sEIT measurements can also be reduced. However, it remains challenging to cope with capacitive coupling between the cable shield and the ground, especially in resistive field conditions. The aim of this study is to deal with this type of capacitive coupling effect by identifying and filtering out sEIT measurements that are strongly affected by capacitive coupling. Based on a correction method for capacitive coupling proposed in a previous study, an approach to estimate measurement errors due to capacitive coupling is presented first. In the second step, a workflow was proposed to calculate the capacitive coupling strength (CCS) for each electrode configuration, which is defined as the ratio of the imaginary part of the impedance induced by capacitive coupling and the imaginary part of the impedance due to the subsurface electrical conductivity. In the final step, measurements with low CCS were selected for inversion and the results were compared with inversion results obtained using the previously developed correction approach. It was found that the filtering method based on CCS is more capable in tackling capacitive coupling compared to using model-based corrections. Spectrally consistent sEIT results up to kHz were obtained using the newly developed filtering method, which were not achieved in previous work using model-based correction.

Novel crosstalk circuit design for high density logic applications

As IC transistors scale down further, physical limitations are restricting performance growth. The contradiction between demands for computing capabilities and challenges in transistor downscaling is exacerbating. This paper proposed a crosstalk circuit design using interconnect coupling capacitance to improve the computing power of chips. Firstly, a valid model of coupling capacitance between metal interconnects is established based on analysis of the factors affecting coupling capacitance. Then, basic crosstalk gates including NAND and NOR are designed by adopting line crosstalk and sampling inverters. Furthermore, complex logic gates and combination circuits are implemented by using the basic crosstalk gates. For verification, a test chip based on line computing is fabricated in 65 nm CMOS technology and the core area is ∼0.019 mm2. The experimental results verified the correctness of the proposed crosstalk gate's logic. Compared with standard logic circuit, the crosstalk NAND or NOR gates reduce the area overhead by 10.6 % and also enhance the circuit's capability of anti-reverse engineering.

Wireless Power Transfer: A simulation-focused exploration

Wireless power transfer (WPT) is leading a technological revolution, redefining how we transmit electrical energy without the usage of cables or connectors. This exploration peeks into various WPT systems, each offering unique benefits and applications. From magnetic inductive coupling for nearby charging to resonant inductive coupling for power transfer across longer distances, and from capacitive coupling for low-power needs to magnetic resonance coupling for mid-range transmission, this paper presents an introduction to the world of WPT. Through simulations in MATLAB and Simulink, we gain insights into various applications like consumer electronics, healthcare, automotive, and more. Looking ahead, we foresee a future where WPT uses sustainable energy practices and creates entirely wireless environments.

A novel charge reconstruction algorithm applied to the HERD prototype silicon charge detector

The High Energy Cosmic-Radiation Detection (HERD) facility is a space astronomy and particle astrophysics experiment planned to be installed on the China Space Station. HERD can detect high-energy cosmic rays ranging from GeV to PeV and high-energy gamma rays. The silicon charge detector (SCD) is one of the subdetectors of HERD, measuring the charge and trajectory of incident ions. An ion beam test of the SCD prototype was conducted at CERN in 2022. A novel charge reconstruction algorithm based on the capacitive coupling was developed to study the charge resolution of the SCD prototype, and compared with the classical reconstruction algorithm.

Design of Capacitive Power Transfer System with Small Coupling Capacitance for Wireless Power Transfer

Wireless power transfer systems play an important role in the application of modern power supply technology. Wireless charging has been widely used in portable devices such as smartphones, laptops, and even some medical devices. Higher system efficiency can be achieved while reducing costs. This article describes the design of a capacitive power transfer (CPT) system using the Class-E amplifier method. When the capacitance of the coupling plate is small, the operation of Class-E amplifiers under Zero-Voltage-Switching (ZVS) conditions is very sensitive to their circuit parameters. By adding an additional capacitor to the Class-E amplifier, the coupling capacitance can be increased, resulting in better circuit performance. The high efficiency of the Class-E amplifier is verified by simulation and experimental results.

Giant magnetoimpedance effect and spin accumulation in conjugated polymeric networks with inhomogeneity

The magnetoimpedance effect allows us to estimate the extent of spin dependent scattering in disordered solids. The change in impedance with respect to applied magnetic field manifests through local change in permeability on the surface and it amplifies at defect sites. The local electrical inhomogeneities are expected to aid this effect through spin dependent scattering. The organic conjugated electrical networks provide scope for producing such inhomogeneities formed by path defects and protonic charge accumulation leading to spin dependent scattering. This hypothesis is investigated in the present work taking polyaniline as a prototype network. The electrical inhomogeneities in the network were controlled by selective oxidation and aging in polyaniline. The Giant Magnetoimpedance (GMI) was observed in the electrically inhomogeneous network with the change in electrical impedance of the order of 50%–60% for lower frequencies with prominent capacitive coupling and a change of the order of 200% at higher frequencies with prominent inductive coupling with the application of magnetic field. However, no spin accumulation was observed in the insulating networks formed by a modified oxidative process. This study is expected to serve as a tool to develop frequency selective spin accumulation based magnetic field sensors and oscillator networks.

Analysis of a capacitance tomography system for object detection and localization

Abstract To ensure safe human-robot cooperation, it is necessary not only to measure the force exerted during contact, but also to monitor an approaching action. This would allow avoiding any unintentional contact through evasive maneuvers and thus prevent possible injuries. In our contribution we analyze a localization system based on capacitance tomography where an approaching object constitutes an electrode of a multi-electrode capacitance. The system processes measured voltages made on the surface of a conductive layer. From this, the location of the capacitive coupling between the object and the layer can be reconstructed, and the position of the object can be estimated. The system’s performance is further analyzed using the Neyman–Pearson detector. To define the performance of the system, for object detection only, the influence of object distance, object area, and number of measurements used on the probability of detection is examined.

Development of a low-power SAR ADC for analog front-end readout circuit of hydrophones

A low-power 16 bit 250KSa/s successive approximation analog-to-digital converter (SAR ADC) is designed. The capacitor array consists of a 2-segment sub-capacitor array and high sampling makes the coupling capacitance a unit capacitance, solving the problem of fractional capacitance mismatch. The power consumption is reduced by introducing a common-mode voltage during the switching process of the capacitor array. The circuit uses a 4-stage pre-amplifier and adds a dynamically latched comparator using output misalignment calibration to ensure high accuracy resolution. Simulated in DB Hitek 0.18 μm process, the Fast Fourier Transform(FFT) simulation results for 4096 points show that the signal-to-noise distortion ratio (SNDR) of the ADC can reach 90.2 dB and the effective number of bits (ENOB) can reach 14.69 bit. The average power consumption is 2.507mW at a supply voltage of 5 V, and this holds significant significance for the long-term deep-sea detection capabilities of sonar systems.

Research on Non-Invasive Voltage Measurement Method Based on Impedance Adaptation

Transformer-based contact voltage measurement requires electrically charged installation during use. Moreover, there are problems with large sizes and restricted installation locations. The current non-contact voltage measurement technology is based on the principle of capacitive coupling in measurement. The capacitance between the probe and the wire is affected by the diameter of the wire and the insulation material. This results in an unstable sensor gain relationship, which leads to low measurement accuracy. This paper proposes a non-contact multi-wire adaptive voltage measurement method, and self-calibration of the sensor gain is achieved through practical measurements. First, the basic principle of capacitively coupled voltage measurement is introduced, from which the existing problems are condensed. An impedance-based adaptive method is proposed, based on which a new sensor probe is developed. The accuracy test reveals that the maximum relative error of voltage amplitude is 0.89 percent, the relative error of phase is 0.38%, and the relative phase error is within 1 degree for a specified voltage range (100 V-300V). The scenario adaptability test shows that the maximum relative error is 1.7% when performing tests on different types of lines. This sensor has the advantages of compactness, convenience, low cost, and high practicality.