Kμ波段硅基MEMS可重构微型天线设计

在硅衬底上设计了频率分别为11.7 GHz和12.7 GH的双波段缝隙天线,此设计利用RF-MEMS开关来实现天线的频率重构;天线结构紧凑、共平面波导馈电,采用IC工艺制作,为下一代无线通讯和天线集成具有重要的参考价值.采用3D电磁模拟软件HFSSR模拟了天线在低频和高频的反射损失分别为29.5 dB和25 dB;并且天线在低频和高频都有较高的辐射效率.     

基于柔性衬底的双端固支梁RF MEMS开关相位特性研究

本文针对衬底弯曲对柔性RF MEMS开关相位特性的影响,提出了一种基于LCP柔性衬底的双端固支梁RF MEMS开关相位特性模型,并从软件仿真和实验验证方面对不同曲率条件下开关的相位偏移进行了深入研究,揭示了柔性衬底弯曲对相位偏移量的影响规律.实验结果表明,当柔性衬底弯曲曲率从0增大到28.6 m-1时,RF MEMS开...     

Electrothermally Actuated RF MEMS Switches Suspended on a Low-Resistivity Substrate

This paper presents an electrothermally actuated lateral resistive-contact switch for application to low-gigahertz-band communication systems. It was manufactured on a standard low-resistivity substrate, and its RF performance was improved by suspending the structures 25 mum from the substrate, which is a strategy for future integration with active devices in the system-on-chip concept. Measured insertion losses are -0.26 dB at 1 GHz and -0.65 dB at 6 GHz, return losses are -29 dB at 1 GHz and -25 dB at 6 GHz, and isolations are -52 dB at 1 GHz and -26 dB at 6 GHz. The device is driven by a metal electrothermal actuator, which achieves large displacements and contact forces at much lower temperatures than traditional polysilicon electrothermal actuators. The RF power handling characteristics are also addressed and measured.     

Novel Reliable RF Capacitive MEMS Switches With Photodefinable Metal–Oxide Dielectrics

In this paper, the design, fabrication, and measurement of reliable low-cost capacitive radio-frequency microelectromechanical systems switches with a novel fabrication approach using direct photodefinable high-k metal oxides are presented. In this approach, a radiation-sensitive metal-organic precursor is deposited via spin coating and converted to a high-k metal oxide via ultraviolet exposure. Measurements of the bridge-type switches have been done up to 40 GHz. These switches are reliable (> 340 million cycles) and exhibited low insertion loss (about 0.3 dB at 20 GHz) and better isolation (about 24 dB at 20 GHz) at frequencies below the resonant frequency as compared to switches that are fabricated using a simple silicon nitride dielectric.     

RF MEMS continuous reversible variable inductor based on a microfluidic network

In this work, RF MEMS continuous reversible variable inductor has been fabricated by using microelectronic technology and lamination process. We review, evaluate and compare this variable inductor with other work. The proposed inductor is a dual circular coil and has an inductance of few nH. The fundamental idea is to place a liquid droplet between the metal turns of a coil in order to modify the capacitive/resistive coupling between metal tracks and hence to change the stored magnetic energy. The SU-8 resin was used to realize the microfluidic channels and Au as metallic tracks. To prove the reversibility of the inductor, two cases were studied: filling and emptying of channels. The tuning range of the inductance is approximately 107 % at 1.6 GHz, making these devices very suitable as building blocks in many RF applications.     

基于LCP衬底的柔性湿度传感器研究

介绍了一种新型柔性电容式湿度传感器.该柔性电容式湿度传感器采用液晶高分子聚合物(LCP)作为衬底,金属铜(Cu)作为叉指电极,聚酰亚胺(PI)作为湿度传感器的湿敏介质.LCP衬底的应用使得该传感器具有良好的柔性和可弯曲性.该柔性湿度传感器与传统硅基湿度传感器相比较具有成本低廉、结构简单、制作方便等优点.该柔性湿度传感器在25℃下的平均灵敏度为0.04%pF/%RH,最大回滞为±4.16%RH,其平均灵敏度在25℃~70℃范围内受温度影响较小.在25℃下其响应时间和恢复时间分别为36 s和39 s.该柔性湿度传感器可以应用于环境湿度检测、人工电子皮肤系统和可穿戴设备等领域.     

Residual Stress Measurement on a MEMS Structure With High-Spatial Resolution

A new approach to the local measurement of residual stress in microstructures is described in this paper. The presented technique takes advantage of the combined milling-imaging features of a focused ion beam (FIB) equipment to scale down the widely known hole drilling method. This method consists of drilling a small hole in a solid with inherent residual stresses and measuring the strains/displacements caused by the local stress release, that takes place around the hole. In the presented case, the displacements caused by the milling are determined by applying digital image correlation (DIC) techniques to high resolution micrographs taken before and after the milling process. The residual stress value is then obtained by fitting the measured displacements to the analytical solution of the displacement fields. The feasibility of this approach has been demonstrated on a micromachined silicon nitride membrane showing that this method has high potential for applications in the field of mechanical characterization of micro/nanoelectromechanical systems     

一种基于MEMS的同位素微电池的新型结构设计与仿真

针对传统同位素微电池的倒三角直槽型或倒金字塔型能量转换结构表面积较小和工作状态不稳定的缺陷.设计了一种垂直侧壁方孔阵列型的能量转换结构,增大了其表面积;并引入电镀这一新型的接触方式,改善了同类传统微电池的工作稳定性.建立了同位素微电池的电流计算公式.基于这种新结构对电池性能仿真得到了能量转换结构的最佳掺杂浓度,结果表明该结构与传统的能量转换结构相比,具有较低的掺杂浓度,较高的开路电压,输出电流和输出功率.     

A top-down design methodology of MEMS varactor for RF applications based on a substrate-induced capacitive model

Due to their excellent quality factor in microwave frequency range, microelectromechanical (MEMS) varactors are an attractive choice for wireless communication engineers for building high performance telecommunication circuits. Significant progress in the technology of MEMS varactor has been reported over the past few years; however a comprehensive design methodology for the varactors based on some performance specifications is not reported. Also, it has been found that for the varactors fabricated with multi user processes (MUMPs), the measured capacitance deviates widely from the predicted value. In this work, it has been shown that a substrate-induced capacitance can change the expected capacitance of the varactor widely and can justify the deviation of the measured values to a good degree of accuracy. Here, a quantitative account of this difference has been presented. The capacitance profile of the varactor fabricated in PolyMUMPs process has been measured and the results show good agreement with the design values; thus indicating a clear influence of substrate induced capacitance on the varactor. Finally, a systematic design methodology of the varactor for a voltage controlled oscillator (VCO) application has been given.

     

A top-down design methodology of MEMS varactor for RF applications based on a substrate-induced capacitive model

Due to their excellent quality factor in microwave frequency range, microelectromechanical (MEMS) varactors are an attractive choice for wireless communication engineers for building high performance telecommunication circuits. Significant progress in the technology of MEMS varactor has been reported over the past few years; however a comprehensive design methodology for the varactors based on some performance specifications is not reported. Also, it has been found that for the varactors fabricated with multi user processes (MUMPs), the measured capacitance deviates widely from the predicted value. In this work, it has been shown that a substrate-induced capacitance can change the expected capacitance of the varactor widely and can justify the deviation of the measured values to a good degree of accuracy. Here, a quantitative account of this difference has been presented. The capacitance profile of the varactor fabricated in PolyMUMPs process has been measured and the results show good agreement with the design values; thus indicating a clear influence of substrate induced capacitance on the varactor. Finally, a systematic design methodology of the varactor for a voltage controlled oscillator (VCO) application has been given.     

一种新的媒体归档存储技术的研究

文章针对媒体存储和管理面临的问题和需求提出并实现了一种新的媒体存储技术——媒体内容寻址存储(MCAS,MediaContentAddressableStorage)。MCAS对媒体对象进行Hash计算得到固定长度的数字代替文件名,Hash和元数据组成一个标准格式的XML文件提供一个媒体对象的数字清单,既便于多个应用程序进行数据交换,又便于用户基于内容检索。MCAS将存储技术和内容管理技术的结合在一起,可针对巨大的视听内容进行数字归档,提高存储系统的搜索性能和效率。     

一种可感知三维力的新型柔性触觉传感器及滑觉识别算法研究

针对智能机器人在软抓取过程中对三维力感知和滑觉识别的需求,以炭黑/石墨烯为敏感材料,硅橡胶为基体,聚酰亚胺为柔性电极,设计了可以实现三维力感知的柔性触觉传感器;同时设计了一种可以实现滑觉识别的基于小波变换-相空间重构-支持向量机(DWT-PSR-SVM)的融合算法.针对机器人软抓取的实验结果表明,该传感器能够有效地检测三维力,通过所设计融合算法能识别在机器人抓取任务中的滑动状态和非滑动状态,可以进一步应用在机器人软抓取的工作中.     

基于平行四边形柔性铰链的新型微量液体粘度测量方法

在分析化学、生物工程、流量计量等领域,微量液体的粘度对工程分析和计算具有重要意义,微量液体粘度测量的方法也在逐渐发展完善。查阅资料发现,目前微量液体测量装置可用于测量粘度值低于150 m Pa·s的微量液体。为了解决微量液体测量装置的粘度测量范围较小的问题,提出一种基于平行四边形柔性铰链的剪切运动的新型粘度测量方法,待测微量液体样本的体积仅为15μL。该方法使用固定在平行四边形柔性铰链上的刚性杆,将刚性杆的探针部分插入液体,在瞬态力的作用下,平行四边形柔性铰链做一维的阻尼振动,带动探针在液体中做剪切运动,由于液体粘滞力,系统的阻尼因数发生变化,液体粘度越大,阻尼因数越大。可以通过标定实验建立二者的关系,实现微量液体的粘度测量。结果表明,此微量液体粘度测量装置的测量范围扩大到了10 m Pa·s～750 m Pa·s,并且相对误差平均为5.8%。证明了该测量装置满足设计的需求,并且能够有效测量微量液体粘度。     

一种新型有机气敏材料的成膜和低温气敏性能

制备了一种新型的有机气敏材料-取代双酞菁镧(Sub-Re(Pc)2),该材料具有优良的溶解性能和成膜性能,无需任何分子支撑剂即可较好地在纯水亚相上形成LB膜.当铺展量为0.5 mg/m2时,崩溃压高达51 mN/m.在10 μm间距的超微电级上制备了18层LB单分子超薄膜,AFM观测证实其表面形貌均匀致密.在气敏响应的测试中,该材料在较低工作温度(10℃)下有灵敏的电子学响应,瞬时响应为3～5s,信号变化达4个数量级.在85℃微热条件下能彻底脱附气体分子,已经具备实际应用价值.     

Determining ITDs Using Two Microphones on a Flat Panel During Onset Intervals With a Biologically Inspired Spike-Based Technique

Using a mockup of a flat panel display, with two omnidirectional microphones we have used intermicrophone time difference (ITD) to determine the azimuthal direction of a sound source (speaker). The speaker is in a noise field in an office-type environment. Bandpass filtering followed by a biologically inspired low latency onset detector (which can cope with a considerable dynamic range) determines the intervals and spectral locations in which an onset is occurring. Direction determination during these onset intervals enables discovery of the onsetting sound's azimuthal angle even in the presence of competing sounds. We compare the results from cross-correlation and novel spike based techniques for determining azimuthal angle during these onset intervals. We note that the system is suitable for real-time implementation.