Liquid Metal Grid Patterned Thin Film Devices Toward Absorption‑Dominant and Strain‑Tunable Electromagnetic Interference Shielding

The demand of high-performance thin-film-shaped deformable electromagnetic interference(EMI)shielding devices is increasing for the next generation of wearable and miniaturized soft electronics.Although highly reflective conductive materials can effectively shield EMI,they prevent deformation of the devices owing to rigidity and generate secondary electromagnetic pollution simultaneously.Herein,soft and stretchable EMI shielding thin film devices with absorption-dominant EMI shielding behavior is presented.The devices consist of liquid metal(LM)layer and LM grid-patterned layer separated by a thin elastomeric film,fabricated by leveraging superior adhesion of aerosol-deposited LM on elastomer.The devices demonstrate high electromagnetic shielding effectiveness(SE)(SE_(T) of up to 75 dB)with low reflectance(SER of 1.5 dB at the resonant frequency)owing to EMI absorption induced by multiple internal reflection generated in the LM grid architectures.Remarkably,the excellent stretchability of the LM-based devices facilitates tunable EMI shielding abilities through grid space adjustment upon strain(resonant frequency shift from 81.3 to 71.3 GHz@33%strain)and is also capable of retaining shielding effectiveness even after multiple strain cycles.This newly explored device presents an advanced paradigm for powerful EMI shielding performance for next-generation smart electronics.

In Situ Atomic Reconstruction Engineering Modulating Graphene-Like MXene-Based Multifunctional Electromagnetic Devices Covering Multi-Spectrum

With the diversified development of big data,detection and precision guidance technologies,electromagnetic(EM)functional materials and devices serving multiple spectrums have become a hot topic.Exploring the multispectral response of materials is a challenging and meaningful scientific question.In this study,MXene/TiO_(2)hybrids with tunable conduction loss and polarization relaxation are fabricated by in situ atomic reconstruction engineering.More importantly,MXene/TiO_(2)hybrids exhibit adjustable spectral responses in the GHz,infrared and visible spectrums,and several EM devices are constructed based on this.An antenna array provides excellent EM energy harvesting in multiple microwave bands,with|S11|up to−63.2 dB,and can be tuned by the degree of bending.An ultra-wideband bandpass filter realizes a passband of about 5.4 GHz and effectively suppresses the transmission of EM signals in the stopband.An infrared stealth device has an emissivity of less than 0.2 in the infrared spectrum at wavelengths of 6-14μm.This work can provide new inspiration for the design and development of multifunctional,multi-spectrum EM devices.

Accuracy and Electromagnetic Safety Evaluation of a Portable Electromagnetic Localization System for Micro Invasive Medical Devices in Vivo

Aiming at localizing the telemetric capsule for detecting gastrointestinal physiological parameters in vivo accurately,a portable alternating current(AC)electromagnetic localization system is designed.To verify the feasibility of the method,the model and construction of the localization system are detailed.And static and dynamic accuracy of the localization system are tested by experiments.Next,we compare the simulating results of the electromagnetic radiation aroused by the localization system with the electromagnetic safety standards of human(ICNIRP guidelines and IEEE standard C95.1-1991).Finally,in terms of the results of the static and dynamic experiments,conclusions are drawn that the accuracy of portable positioning system is high(less than 10 mm)enough to satisfy the localization need of the micro invasive medical devices in vivo,and there is no harm of electromagnetic radiation to human.

Effects of medically generated electromagnetic interference from medical devices on cardiac implantable electronic devices: A review

As cardiac implantable electronic devices(CIED)become more prevalent,it is important to acknowledge potential electromagnetic interference(EMI)from other sources,such as internal and external electronic devices and procedures and its effect on these devices.EMI from other sources can potentially inhibit pacing and trigger shocks in permanent pacemakers(PPM)and implantable cardioverter defibrillators(ICD),respectively.This review analyzes potential EMI amongst CIED and left ventricular assist device,deep brain stimulators,spinal cord stimulators,transcutaneous electrical nerve stimulators,and throughout an array of procedures,such as endoscopy,bronchoscopy,and procedures involving electrocautery.Although there is evidence to support EMI from internal and external devices and during procedures,there is a lack of large multicenter studies,and,as a result,current management guidelines are based primarily on expert opinion and anecdotal experience.We aim to provide a general overview of PPM/ICD function,review documented EMI effect on these devices,and acknowledge current management of CIED interference.

Call for Papers 2009 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD’09)

We are delighted to announce that the 2009 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD’09) will be held on 25-27 September 2009 in Chengdu, China. ASEMD’09 aims to be

Call for Papers 2009 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD’09) 25-27 September 2009, Chengdu, China

We are delighted to announce that the 2009 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD’09) will be held on 25-27 September 2009 in Chengdu, China. ASEMD’09 aims to be a

Oxidative Molecular Layer Deposition Tailoring Eco-Mimetic Nanoarchitecture to Manipulate Electromagnetic Attenuation and Self-Powered Energy Conversion

Advanced electromagnetic devices,as the pillars of the intelligent age,are setting off a grand transformation,redefining the structure of society to present pluralism and diversity.However,the bombardment of electromagnetic radiation on society is also increasingly serious along with the growing popularity of"Big Data".Herein,drawing wisdom and inspiration from nature,an eco-mimetic nanoarchitecture is constructed for the first time,highly integrating the advantages of multiple components and structures to exhibit excellent electromagnetic response.Its electromagnetic properties and internal energy conversion can be flexibly regulated by tailoring microstructure with oxidative molecular layer deposition(oMLD),providing a new cognition to frequency-selective microwave absorption.The optimal reflection loss reaches≈−58 dB,and the absorption frequency can be shifted from high frequency to low frequency by increasing the number of oMLD cycles.Meanwhile,a novel electromagnetic absorption surface is designed to enable ultra-wideband absorption,covering almost the entire K and Ka bands.More importantly,an ingenious self-powered device is constructed using the eco-mimetic nanoarchitecture,which can convert electromagnetic radiation into electric energy for recycling.This work offers a new insight into electromagnetic protection and waste energy recycling,presenting a broad application prospect in radar stealth,information communication,aerospace engineering,etc.

Flexible Nanocomposite Conductors for Electromagnetic Interference Shielding

With the extensive use of electronic communication technology in integrated circuit systems and wearable devices, electromagnetic interference(EMI) has increased dramatically. The shortcomings of conventional rigid EMI shielding materials include high brittleness, poor comfort, and unsuitability for conforming and deformable applications. Hitherto, flexible(particularly elastic) nanocomposites have attracted enormous interest due to their excellent deformability. However, the current flexible shielding nanocomposites present low mechanical stability and resilience, relatively poor EMI shielding performance, and limited multifunctionality. Herein, the advances in low-dimensional EMI shielding nanomaterials-based elastomers are outlined and a selection of the most remarkable examples is discussed. And the corresponding modification strategies and deformability performance are summarized. Finally, expectations for this quickly increasing sector are discussed, as well as future challenges.

Introduction to Mesh Based Generated Lumped Parameter Models for Electromagnetic Problems using Triangular Elements

This paper is an introduction to mesh based generated reluctance network modeling using triangular elements.Many contributions on mesh based generated reluctance networks using rectangular shaped elements have been published,but very few on those generated from a mesh using triangular elements.The use of triangular elements is aimed at extending the application of the approach to any shape of modeled devices.Basic concepts of the approach are presented in the case of electromagnetic devices.The procedure for coding the approach in the case of a flat linear permanent magnet machine is presented.Codes developed under MATLAB environment are also included.

Design and fabrication of a bistable electromagnetic microactuator

An electromagnetic microactuator with two stable positions is presented. The actuator consists of a cantilever beam with two free ends, a torsional beam with two fixed ends, planar coils and permanent magnets. The cantilever beam has two stable positions due to the use of permanent magnets. With electromagnetic actuation arising from the planar coils, the cantilever beam will switch from one stable position to the other. Mechanical and magnetic analysis are carried out on the actuator, and the device with a size of 2.2 mm × 2.5 mm is fabricated with the UV-LIGA technology. The test results show that a current pulse with an amplitude of 70 mA is needed for actuator＇ s switching between the two stable states, and the switching time is no more than 6 ms. Displacement of the end of cantilever is about 15 μm.

Introduction to Mesh Based Generated Lumped Parameter Models for Electromagnetic Problems

This paper is an introduction to mesh based generated reluctance network modeling.An overview of scientific works which led to the development of this approach is first presented.Basic concepts of the approach are then presented in the case of electromagnetic devices.A step-by-step procedure for coding the approach in the case of a flat linear permanent magnet machine is presented.Codes developed under MATLAB and Scilab environments are also included.

Analysis and Calculation for Heating and Temperature Rise of Magnetic Levitation Device

准确的热分析是磁悬浮系统电磁装置优化设计、防止过热的前提。提出了基于等效热路模型的电磁装置发热及温升计算方法,并与基于＂场＂的仿真分析结果进行比较,验证其正确性。首先,利用ANSYS软件建立电磁装置的瞬态温度场模型,并将装置中动铁心随大轴旋转时与空气产生的风摩擦损耗包含在模型中,通过仿真分析,得到电磁装置温度分布;然后,通过对散热路径的分析建立了电磁装置的等效热路模型,从＂路＂的角度计算出本电磁装置各位置的温升;最后,将基于＂路＂的计算结果与基于＂场＂的仿真结果进行了比较分析,各部分温升误差均在允许范围内,验证了等效热路模型计算电磁装置发热及温升方法的准确性和可行性。在基于＂场＂和＂路＂的两种分析中,均考虑了电阻率随温升的变化,散热分析中均计及了导热系数和对流散热系数随温度的变化。

Flexible and breathable 3D porous SSE/MXene foam towards impact/electromagnetic interference/bacteria multiple protection performance for intelligent wearable devices

As intelligent wearable devices,they will inevitably be subjected to various damages and disturbances from the external environment during daily use.Therefore,it is urgent to develop safeguarding materials with multiple protective properties.Herein,this work developed a flexible and breathable three-dimensional(3D)porous shear stiffening elastomer(SSE)/MXene(M-SSE)foam with impact/electromagnetic interference(EMI)/bacteria multiple protection performance for intelligent wearable devices.The continuous conductive MXene network in the 3D SSE porous structure made M-SSE foam exhibit excellent electromagnetic interference shielding property with a high shielding effectiveness of 34 dB.Attributed to the shear stiffening effect of porous SSE matrix,M-SSE foam possessed unique anti-impact and protection properties.The energy dissipation rate reached up to more than 85%,illustrating M-SSE foam could effectively attenuate the external impact force and absorb the impact energy.Inherited from the excellent photothermal performance of MXene,M-SSE foam achieved a considerable saturated temperature of 98℃ under 0.57 W/cm^(2) laser power.Therefore,M-SSE foam showed extraordinary antimicrobial property for Staphylococcus aureus according to the principle of photothermal sterilization.Finally,for the development of intelligent wearable devices,conductive MSSE foam could be used as an intelligent sensor to monitor various human movements owing to the highly sensitive property.This work greatly expanded the application prospect of multifunctional protective materials in various complex environments and promoted the development of multifunctional smart wearable devices in protection field.

Electromagnetic Simulation for the Diagnosis of Lipoprotein Density in Human Blood, a Non-Invasive Approach

With the rise in prevalence of Type II diabetes throughout the world, an increasing need for a portable monitoring system for both blood glucose and lipoprotein concentrations is in demand. Recent work has led to non-invasive wearable devices for monitoring changes in blood glucose concentrations using electromagnetic (EM) waves. However, this still fall short as a means of monitoring cholesterol levels in diabetic patients. The EM study on human tissues emphasized here may also relate to the safety guidelines applied to cellular communications, power lines, and other EM applications. The specific absorption rate (SAR) for the power of the non-ionizing frequency must not exceed a threshold as it impacts DNA and can lead to cancerous tissues. In this study, we used COMSOL software for the investigation of the viability of using EM within the frequency range of 64 MHz-1 GHz as a means of monitoring the transmission properties of human blood and lipoprotein. In this approach, wave equations were solved within blood and lipoprotein boundaries. Research parameters, including frequency range, Power input (SAR), and lipoprotein densities, were investigated. The transmission properties, produced by the electrical and thermal characteristics of these physiological parameters, have led to proper diagnosis of lipoprotein density. Within the frequency range of 64 MHz to 1 GHz, and for a power range of 0.1 to 0.6 SAR, lipoprotein density from 1.00 g/mL to 1.20 g/mL was considered. A 2D model, with an antenna source that supplied the electromagnetic waves to human tissues, was created for the simulations. These were used for the study of the transmission properties of the EM energy into the blood and lipoprotein tissues. While the range of magnetic flux values between simulations varies only slightly or not at all, the distribution of these values is impacted by given parameters. As such, a device capable of comparing magnetic flux values and penetration depths could easily distinguish between samples of different lipoprotein densities. The results obtained in this study can be accommodated non-invasively by human tissues, and can be produced in a practical model using wearable devices. A practical model is proposed for future consideration.

A Method for Automating Signal Analysis from Therapeutic Devices

Many methods exist for cardiac and neural signal feature extraction and identification, but a published method for validation of therapeutic medical devices by computer analysis of their signals can be seldom found. This paper presents a simple, fast algorithm to extract the electrical stimulation including pulse width, exponential decay, and time between pulses from neurostimulators, pacemakers, implantable cardioverter defibrillators (ICDs), and transcutaneous electric nerve stimulators (TENS). An experimental validation demonstrated the automated analysis provide means to expedite device validation testing. In the future studies, the algorithm should be improved for its robustness and checked for analysis of signals with lower SNR. A figure of merit is provided to expedite electromagnetic compatibility (EMC) tests on the devices to ensure proper operation in the presence of electromagnetic emitters.

考虑精确磁通的电磁加载装置等效磁路建模

为提高电磁加载装置在控制应用时的模型预测快速性与精确性,考虑电磁加载装置硅钢片表面涡流磁场生成因素与不同轴偏心下有效气隙长度,采用非线性方程拟合硅钢片磁化曲线,建立包含磁极边缘效应、磁极铁心、转子硅钢片动态磁阻与涡流磁场的电磁加载装置非线性等效磁路模型。研究了硅钢片表面涡流磁场生成因素与气隙磁场分布,并与有限元仿真结果比较分析。应用该模型在水润滑轴承试验台上进行电磁加载力测试试验。研究结果表明:等效磁路法对磁场分布的表征与有限元法一致,且对气隙的计算更为精确;电磁加载力稳态误差小于4%,响应时间低于0.55 s。

电力电子系统中的电磁兼容专辑主编述评

SiC、GaN新一代宽禁带功率半导体在推动电力电子设备快速高频化、高效化和小体积化的同时,更容易干扰敏感负载、影响无线电通讯,乃至危害自身安全、可靠运行,从而给电力电子设备内外部的电磁兼容性能带来极大的压力和挑战。近年来,功率开关器件的射频特性、磁性器件的宽频带电磁模型、开关电源电磁辐射机理、无线电能传输近场特性、新型电磁干扰EMI(electromagnetic interference)滤波器设计成为研究热点,并受到了学术界及工业界的持续关注。《电源学报》特别推出“电力电子系统中的电磁兼容”专辑,以期推进电力电子系统电磁兼容分析与设计领域难点和热点问题的探讨。

考虑动态接触电阻的电磁能推进装置运动和温度特性研究

在电磁能推进装置工作过程中,电枢与轨道间的接触电阻动态变化对系统性能有着重要影响。针对现有研究多依赖于Holm接触电阻理论并以电枢静止状态为基础的局限性,采用有限元和控制变量法研究实际推进情况下枢轨动态接触电阻对电磁能推进装置运动和温度特性的影响。首先,通过实验获取膛口电压、电流、电枢速度和位移等关键参数。其次,利用改进的完全自适应噪声集合经验模态分解(improved complete ensemble empirical mode decomposition with adaptive noise, ICEEMDAN)-小波阈值组合算法对所获得信号进行降噪处理,计算实际工况下的动态变化接触电阻。分别建立考虑枢轨动态接触电阻与不考虑接触电阻情况下的电磁热力耦合有限元模型,通过对比计算结果得到动态接触电阻对电枢运动和温度特性的影响。最后与实验结果进行对比,发现动态接触电阻是影响推进装置性能的重要因素,随着电枢位移的增加,接触电阻对运动特性的影响逐渐增加。另外,动态接触电阻的存在还会使电枢表面的温度迅速升高,电枢尾翼容易发生烧蚀,进而影响电枢的加速性能。该研究为进一步分析极端条件下动态接触电阻对电磁能推进装置的性能影响提供理论支持。

磁脱扣器动作响应分析及储能电容匹配设计

驱动电路与磁脱扣器是电磁式漏电保护器的核心组件,磁脱扣器需与储能电容匹配。在电磁式漏电保护器基本工作原理分析的基础上,建立磁脱扣器的数学模型与有限元计算模型,根据激磁安匝变化进行衔铁响应状态分析,仿真不同线圈激励形式下磁脱扣器动作响应状态。研究衔铁角动量与角位移变化特征,根据无激励时衔铁释放临界角动量与角位移关系,确定不同线圈激励形式下的衔铁临界释放条件。研究电容电压激励源下衔铁所受力矩冲量的变化规律,分析电容及其储能对衔铁释放响应状态的影响,根据临界储能最小的原则确定电容匹配,可以降低衔铁可靠释放所需储能。通过对磁脱扣器样机进行实验测试,验证了理论分析与仿真计算的正确性。

大定源回线装置瞬变电磁法在煤矿采空区探测中的应用

该文通过研究大定源回线装置瞬变电磁法在煤矿采空区探测中的应用,旨在提高煤矿采空区探测的效率和准确性。深入探讨大定源回线装置瞬变电磁法的原理和工作机制。在此基础上,设计并实施适用于煤矿采空区的探测方案,并通过试验进行验证。结果表明,大定源回线装置瞬变电磁法在煤矿采空区探测中取得显著的效果。大定源回线装置瞬变电磁法具有高效、准确、可靠的特点,能够快速识别采空区位置,为后续生产建设提供保障,同时也为其他煤矿采空区勘察提供参考。