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.

Electronically Tunable Minimum Component Biquadratic Filters for Interface Circuits

In this paper, two new electronically tunable filter configurations are proposed. The proposed filters operate current-mode (CM), voltage-mode (VM), transimpedance-mode (TIM) and transadmittance-mode (TAM). The first configuration realizes second-order VM band-pass and TAM high-pass filter characteristics from the same configuration. The second one realizes second-order TIM band-pass and CM low-pass filter characteristics from the same configuration. They also use minimum number of electronic components (two capacitors and one active component namely;current controlled current difference transconductance amplifier). The workability of the proposed structures has been demonstrated by simulation results.

Wavelength-tunable organic semiconductor lasers based on elastic distributed feedback gratings

Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the distributed feedback gratings for fine tuning the lasing wavelength. Notably, elastic lasers based on three typical light-emitting molecules show com-parable lasing threshold values analogous to rigid devices and a continuous wavelength tunability of about 10 nm by mechanic-al stretching. In addition, the stretchability provides a simple solution for dynamically tuning the lasing wavelength in a spec-tral range that is challenging to achieve for inorganic counterparts. Our work has provided a simple and efficient method of fab-ricating tunable organic lasers that depend on stretchable distributed feedback gratings, demonstrating a significant step in the advancement of flexible organic optoelectronic devices.

Pseudohalide induced tunable electronic and excitonic properties in two-dimensional single-layer perovskite for photovoltaics and photoelectronic applications

Two-dimensional(2D) layered organic-inorganic hybrid perovskites have attracted much more attention for some applications than their three-dimensional(3D) perovskite counterparts due to their promising thermal and moisture stabilities.In particular, the 2D perovskite devices have shown better promise for optoelectronic applications.However, tunability of optoelectronic properties is often demanded to improve the device performance.Herein, we adopt a newly method to tune the electronic properties of 2D perovskite by introducing pseudohalide into the structure.In this work, we designed a pseudohalidesubstituted 2D perovskite by substituting the out-of-plane halide with pseudohalide and studied the electronic and excitonic properties of 2D-BA2MX4 and 2D-BA2MX2Ps2(M=Ge^(2+), Sn^(2+), and Pb^(2+);X=I;Ps=NCO, NCS, OCN, SCN, Se CN).We revealed the dependence of electronic properties including band gaps, composition of band edges, bonding characteristics, work functions, effective masses, and exciton binding energies on different pseudohalides substituted in 2D perovskite.Our results indicate that the substitution of pseudohalide in 2D perovskites is energetically favorable and can significantly affect the bonding characteristics as well as the CBM and VBM that often play major role in determining their performance in optoelectronic devices.It is expected that the pseudohalide substitution will be helpful in developing more advanced optoelectronic device based on 2D perovskite by optimizing band alignment and promoting charge extraction.

Design and Analysis of a Power Efficient Linearly Tunable Cross-Coupled Transconductor Having Separate Bias Control

A common current source, generally used to bias cross-coupled differential amplifiers in a transconductor, controls third harmonic distortion (HD3) poorly. Separate current sources are shown to provide better control on HD3) . In this paper, a detailed design and analysis is presented for a transconductor made using this biasing technique. The transconductor, in addition, is made to offer high Gm, low power dissipation and is designed for linearly tunable Gm with current mode load as one of the applications. The circuit exhibits HD3) of less than –43.7 dB, high current efficiency of 1.18 V-1 and Gm of 390 μS at 1 VGp-p @ 50 MHz. UMC 0.18 μm CMOS process technology is used for simulation at supply voltage of 1.8 V.

二维MXenes材料在柔性光电探测器中的应用展望

二维过渡金属碳/氮化物(MXenes)自2011年被首次报道以来,凭借其特殊的二维层状结构、优异的导电性和电化学性能在能源、催化、传感、电磁屏蔽和微波吸收等领域吸引了极大关注。近几年,随着对该材料认识的不断加深,其在光电领域的研究也不断深入。与其它领域不同,光电器件聚焦于延伸MXenes材料半导体性质,通过设计表面官能团、精准控制层数等来打开材料带隙,从而使其从金属性质转变为半导体性质。本文主要围绕MXenes材料的光电性质,介绍其在柔性光电子器件中的应用,系统阐述MXenes材料在透明电子器件、光电探测器、图像传感器、光电晶体管、人工神经视觉网络系统的应用前沿现状与趋势,并展望了MXenes基柔性光电器件面临的挑战以及未来发展前景。

Interlayer engineering in 3D graphene skeleton realizing tunable electronic properties at a highly controllable level for piezoresistive sensors

Three-dimensional(3D)graphene is a promising active component for various engineering fields,but its performance is limited by the hidebound electrical conductivity levels and hindered electrical transport.Here we present a novel approach based on interlayer engineering,in which graphene oxide(GO)nanosheets are covalently functionalized with varied molecular lengths of diamine molecules.This has led to the creation of an unprecedented class of 3D graphene with highly adjustable electronic properties.Theoretical calculations and experimental results demonstrate that ethylenediamine,with its small diameter acting as a molecular bridge for facilitating electron transport,has the potential to significantly improve the electrical conductivity of 3D graphene.In contrast,butylene diamine,with its larger diameter,has a reverse effect due to the enlarged spacing of the graphene interlayers,resulting in conductive degradation.More importantly,the moderate conductive level of 3D graphene can be achieved by combining the interlayer spacing expansion effect and theπ-electronic donor ability of aromatic amines.The resulting 3D graphene exhibits highly tunable electronic properties,which can be easily adjusted in a wide range of 2.56-6.61 S·cm^(-1)compared to pristine GO foam(4.20 S·cm^(-1)).This opens up new possibilities for its use as an active material in a piezoresistive sensor,as it offers remarkable monitoring abilities.

Theoretical Studies of Electron Paramagnetic Resonance Parameters for Cr^4＋ Ions in Ca2GeO4 Crystals

The electron paramagnetic resonance (EPR) parameters (zero-Geld splitting Dand g factors g_‖, g_⊥) of Cr~(4+) ions in Ca_2 GeO_4 crystals have been calculated from thecomplete high-order perturbation formulas of EPR parameters for a 3d~2 ion in trigonal MX_4clusters. In these formulas, in addition to the contributions to EPR parameters from the widely usedcrystal-field (CF) mechanism, the contributions from the charge-transfer (CT) mechanism (which areoften neglected) are included. From the calculations, it is found that for the high valence state3d~n ions in crystals, the reasonable explanation of EPR parameters (in particular, the g factors)should take both the CF and CT mechanisms into account.

基于VDTA的混合多模式双二阶滤波器的设计

针对各类核探测仪的供电电源系统和核能谱测量仪的前端电子线路广泛采用的滤波技术,提出了一种设计混合多模式双二阶滤波器的新方法。首先通过分析新的有源元件——电压差跨导放大器(VDTA)的一般工作原理,提出了一种采用CMOS晶体管实现VDTA的电路;然后基于实现的VDTA模块,设计了采用两级VDTA模块实现单输入、三输出或三输入、单输出电子可调混合多模式双二阶滤波器。通过选择输入端,该滤波器可以产生5种不同的电压和跨导纳模式滤波器功能,实现低通、带通、高通、带阻和全通5种不同的滤波信号。同时对滤波器的有限频率效应、稳定性条件和寄生元件效应进行了分析;仿真实验结果验证了所设计滤波器的性能,表明了理论设计的正确性和有效性。

Facile intercalation of alkali ions in WO_(3)for modulated electronic and optical properties:Implications for artificial synapses and chromogenic application

Tungsten oxides(WO_(3))are widely recognized as multifunctional systems owing to the existence of rich polymorphs.These diverse phases exhibit distinct octahedra-tilting patterns,generating substantial tunnels that are ideally suited for iontronics.However,a quantitative comprehension regarding the impact of distinct phases on the kinetics of intercalated conducting ions remains lacking.Herein,we employ first-principles calculations to explore the spatial and orientational correlations of ion transport inγ-and h-WO_(3),shedding light on the relationship between diffusion barriers and the size of the conducting ions.Our findings reveal that different types and concentrations of alkali-metals induce distinct and continuous lattice distortions in WO_(3)polymorphs.Specifically,γ-WO_(3)is more appropriate to accommodate Li+ions,exhibiting a diffusion barrier and coefficient of 0.25 eV and 9.31×10^(-8)cm^(2)s^(-1),respectively.Conversely,h-WO_(3)features unidirectional and sizeable tunnels that facilitate the transport of K+ions with an even lower barrier and a high coefficient of 0.11 e V and 2.12×10^(-5)cm^(2)s^(-1),respectively.Furthermore,the introduction of alkali-metal into WO_(3)tunnels tends to introduce n-type conductivity by contributing s-electrons to the unoccupied W 5d states,resulting in enhanced conductivity and tunable electronic structures.These alkali metals in WO_(3)tunnels are prone to charge transfer,forming small polaronic states and modulating the light absorption in the visible and nearinfrared regions.These tunable electronic and optical properties,combined with the high diffusion coefficient,underscore the potential of WO_(3)in applications such as artificial synapses and chromogenic devices.

数控电调带通滤波器的设计与制作

设计了一种新型电调谐带通滤波器,研究了数字信号控制滤波器电调谐的技术。采用数模转换器和高压运放实现数字信号与直流电压的转换;以变容二极管作为调谐元件;带通滤波器采用梳状微带线结构,并给出了结构参数。最后制作了一个由8位二进制编码控制的电调谐带通滤波器,其中心频率在300～1200MHz可调。测试结果与理论设计基本吻合。

太赫兹自由电子激光光腔光子晶体镜的设计

利用传输矩阵法对太赫兹自由电子激光光腔光子晶体镜进行了模拟设计,中心波段在1～3THz。对光腔镜的光子晶体结构参数如介质厚度、层数、折射率与反射率的关系等进行了研究,并给出了一维光子晶体用于高反镜的设计方法。通过对耦合输出镜光子晶体中引入缺陷层情况的数值模拟,发现通过对缺陷层的调节设计,可以实现耦合输出率的可调谐;并给出了可用于THz自由电子激光光腔耦合输出镜的调节方法。通过对介质层厚度的调节设计,可以实现反射光谱的整体移动,从而实现宽谱可调谐,扩大了高反镜及耦合输出镜的调节范围。

新型BST薄膜可调带阻滤波器

提出了一种基于共面传输线结构的新型带阻滤波器,利用该结构在沉积有钛酸锶钡(BST—0.5)薄膜的氧化镁基片上设计并制作了一个可调带阻滤波器。测试结果表明,在30V的外加偏压下,带阻滤波器的传输特性曲线向高频方向整体移动了190MHz,其形状基本保持不变。

基于OTA和CCCII的电流模式可调谐滤波器

设计了一种新颖的双二阶电流模式通用滤波器结构,该滤波器仅包含有源器件OTA、CCCII和接地电容,电路结构简单,与VLSI工艺兼容,便于集成,可实现同时低通、高通、带通、带阻、全通等滤波功能;Q和ω0可以互相不影响的独立调节。采用PSPICE软件仿真分析了所提电路的性能。

电调谐CCCⅡ-C电流模式二阶带通滤波器

本文提出一种新的特征参数可被直流电流调谐的CCCⅡ-C电流模式二阶带通滤波器。它是在基本带通滤波器的基础上增加一个反馈电流放大器,通过调节放大器的放大系数A来调谐滤波器的截止频率,品质因素等参数。该电路由4个CCCⅡ及2个接地电容元件构成,无需接任何电阻元件,具有很低的有源和无源灵敏度。滤波器的Spectre仿真结果表明所提出的电路设计原理和实现方案正确可行。

用热应力法研究二氧化碲晶体表面连接层材料的特性

以声光晶体TeO_2为衬底,设计并研制了1 300~3 400nm波段超宽带减反射膜.从薄膜热应力理论出发,建立膜层热应力受力示意图,结合TeO_2晶体的特性和力矩判定方法,采用解析法逆向计算分析薄膜材料的热膨胀系数及杨氏模量.实验验证表明：所制备的膜层附着力在1300~3400nm波段平均透过率为96.8%;在相同工艺条件下,采用连接层所制备的薄膜附着力更好,可以解决脱膜问题,满足相应的附着力检测要求.

一种新型CMOS电调谐第二代电流传输器(ECCII)

提出了一种新型高线性宽调谐范围的CMOS电调谐第二代电流传输器(ECCII),通过引入两个电流平方电路,使其电流增益能够通过直流偏置连续可调,0<k≤2。并采用TSMC0.35μmCMOS工艺参数,±1.5 V供电电源条件下对ECCII进行了HSPICE模拟,结果表明,vX/vY和iZ/iX的-3 dB带宽分别为85 MHz和61 MHz,功耗为5.1 mW。该电路在可调谐连续时间电流模式滤波器设计中有广泛的应用前景。

叉指式高Q值可变电容仿真设计

提出了一种叉指式微机电系统（MEMS）可变电容设计方案，并从结构、电学特性、工艺三方面进行了仿真设计。由仿真结果可知：驱动电压为67V时，该设计理论电容可调率3．45，电容调节范围88．16～392．19iF，谐振频率36GHz，Q值223（1GHz），反射衰减0．00225dB，插入损耗42．75dB．与其他形式可变电容相比，该设计理论电容具有高Q值、高电容可调率和工艺简单的技术优势。

一种双面周期开槽型可调太赫兹带通滤波器

为实现低成本高效率的可调太赫兹带通滤波器,采用太赫兹时域波谱系统实验研究了一种在薄铝片上制作的中心开通槽两边双面对称周期性开浅槽的结构.实验结果表明由于双面耦合伪表面等离子体激元的增强透射效应,该滤波器垂直入射时在0.33THz处获得超过95%的高透射率,其透射波的发散角在5°左右.并且当滤波器侧向斜入射时透射峰一分为二,低频透射峰红移而高频透射峰蓝移;当滤波器俯仰方向斜入射时透射峰蓝移.

基于枝节加载多模谐振器的电调微波滤波器设计

针对认知无线电技术对射频微波滤波器的新要求,提出了一种基于枝节加载多模谐振器的电调微波滤波器;该电调微波滤波器由一个枝节加载微带多模谐振器和变容二极管组成,实现了滤波器的小型化;在分析枝节加载微带多模谐振器的基础上,通过在微带谐振器两端和加载枝节上加载变容二极管的方法,设计了枝节加载的电调多模微带谐振器,并提出了复杂微带谐振器谐振特性的分析方法;采用源和负载耦合的方法在通带右边引入一传输零点;通过在源和负载端放置耦合线的方法,提高了滤波器的通带选择性;针对滤波器带外衰减小的问题,引入一种新型的频变馈电结构,改善了滤波器的带外衰减特性;通过优化仿真确定了电调滤波器的尺寸参数;仿真验证了该滤波器的特性,当变容二极管的可调范围为2~10 pf时,滤波器的频率可调范围为2.10~2.40 GHz,频率变化范围为300 MHz。