石墨烯谐振式振动测量研究进展

石墨烯是一种新型的超薄材料,单层石墨烯理论厚度仅为0.335 nm,基于石墨烯优异的材料特性和机械性能,可望设计制作出结构优、性能佳的石墨烯谐振敏感结构,实现超高灵敏度振动测量。本文就石墨烯谐振式振动测量研究进展进行综述,包括石墨烯谐振式振动测量研究现状、石墨烯谐振器的实验研究和理论分析等。振动测量在航空航天、汽车、微电子、建筑等方面具有普遍而重要的需求,探索研究微纳结构、超高灵敏度的石墨烯振动测量具有十分重要的理论研究意义和应用价值。     

一种基于光纤F-P腔的石墨烯谐振式压力传感器

谐振式传感器具有良好的重复性、分辨率和稳定性,全光纤谐振式微型传感器则集合了微纳结构与光纤传感特性两者的优点。石墨烯作为近年来发现的一种新型材料,具有良好的热学和力学特性,可以作为谐振式传感器中的敏感元件。本文提出了一种基于光纤F-P结构的石墨烯谐振式压力传感器,其兼具微机械传感器和光纤谐振器的优点,具有较高的谐振频率,在测量压力的实验中展现出良好的性能,压力灵敏度最高可达2. 93Hz/Pa,具有重要的应用价值。     

石墨烯谐振式微质量传感器研究进展

微质量传感器可以用于毒害气体,纳米颗粒的检测,被广泛用于环境检测,医疗诊断等领域。近年来,基于石墨烯材料的微质量传感器因为其大的表面积体积比,低电子噪声,及优异的吸附性被广泛研究。本文针对一类基于谐振原理的超高灵敏度石墨烯微质量传感器展开综述,重点论述了石墨烯谐振器的结构,激振拾振方案,质量敏感特性等问题,总结了关于石墨烯谐振式微质量检测的进展及挑战。     

石墨烯谐振特性研究进展

石墨烯具有优异的谐振特性, 相关研究对谐振式传感器的未来发展和应用具有重要意义。目前石墨烯谐振特性的研究方法主要包括实验测量方法和理论分析方法, 后者又分为基于纳米力学的分析方法和基于经典力学的分析方法。由于利用实验精确获取石墨烯的谐振特性比较困难, 相关的理论研究和总结十分重要。本文就石墨烯谐振特性的研究进展进行综述, 包括谐振式石墨烯传感器的实验和理论分析方法的分类、现状、优缺点以及发展趋势等。     

用于挥发性有机化合物探测的微悬臂梁传感器

在研制成功的用于化学气体探测的热驱动微悬臂梁谐振器的基础上,提出了基于这种微悬臂梁谐振器,并以聚合物涂层作为挥发性有机化合物吸附敏感层的谐振式气体传感器.利用3种聚合物材料：聚氧化乙烯（PEO）、聚乙烯醇（PVA）和聚乙二醇乙醚醋酸酯（PEVA）,在微悬臂梁谐振器上制备气体敏感层,探测6种挥发性有机化合物：甲苯、苯、乙醇、丙酮、己烷和辛烷.通过有限元分析估计了聚合物涂层的工作温度.用喷射法制备了PVA和PE-VA涂层,用点滴法制备了PEO涂层.测试了传感器的开环幅频特性,实验检测了气体传感器的谐振频率变化与分析物蒸气浓度的关系以及传感器对相对湿度的响应,分析了传感器的灵敏度和线性度.实验结果表明,这种涂覆聚合物敏感层的热驱动微悬臂梁谐振器为探测挥发性有机化合物提供了良好的平台.根据实验结果,可开发几种基于不同聚合物敏感层的高灵敏度微型气体传感器.     

一种用于复杂环境下的高精度微型谐振式压力传感器北大核心CSCD

微谐振式压力传感器因其体积小、精度高等特点而被广泛研究,本文基于谐振器在不同压力载荷下侧向振动时其等效刚度随轴向应力的改变而变化的原理,设计了一种静电激励/电容检测的谐振式压力传感器。本设计采用的谐振器结构与现有研究不同,通过在谐振梁的两边设计了两根侧梁用于抑制谐振器的Z向位移,提高了传感器的稳定性,并且双面梳齿结构和复合温敏梁可进一步优化传感器检测灵敏度等性能。在ANSYS WORKBENCH仿真平台下对其进行分析与验证,结果表明:侧梁可有效地抑制谐振器的Z向位移,在0~100 MPa范围内谐振器具有良好的正向应力特性;传感器基础谐振频率为29.834 kHz,在0~120 kPa范围内灵敏度可达29.6Hz/kPa,且最大过压1.5×FS时仍具备频率稳定性,这表明该传感器可应用于对灵敏度、抗过压等性能有更高要求的复杂环境中。     

一种用于复杂环境下的高精度微型谐振式压力传感器

微谐振式压力传感器因其体积小、精度高等特点而被广泛研究,本文基于谐振器在不同压力载荷下侧向振动时其等效刚度随轴向应力的改变而变化的原理,设计了一种静电激励/电容检测的谐振式压力传感器。本设计采用的谐振器结构与现有研究不同,通过在谐振梁的两边设计了两根侧梁用于抑制谐振器的Z向位移,提高了传感器的稳定性,并且双面梳齿结构和复合温敏梁可进一步优化传感器检测灵敏度等性能。在ANSYS WORKBENCH仿真平台下对其进行分析与验证,结果表明:侧梁可有效地抑制谐振器的Z向位移,在0~100 MPa范围内谐振器具有良好的正向应力特性;传感器基础谐振频率为29.834 kHz,在0~120 kPa范围内灵敏度可达29.6Hz/kPa,且最大过压1.5×FS时仍具备频率稳定性,这表明该传感器可应用于对灵敏度、抗过压等性能有更高要求的复杂环境中。     

谐振式微机械惯性传感器

对几种典型的谐振式加速度微传感器和微陀螺的结构、工作原理等方面进行了概述,分析了各自的应用特点。从中反映出谐振式微惯性传感器具有优良的特性,必有广阔的应用和发展前景。     

一种新型的谐振梁频率测量方法研究

谐振梁是一种应用广泛的谐振器。谐振式传感器可以通过测量谐振梁谐振频率的变化,解算谐振梁所受的轴向载荷的大小,从而达到测量目的。目前谐振梁常用的频率测量方法对于动态测量问题的效果并不理想,在很多应用场合都受到限制。本文针对双端固支型谐振梁的频率测量问题,设计了一种基于希尔伯特变换的频率测量方法。使用数值方法对谐振梁振动方程进行求解,获得多种典型的测试信号。仿真实验表明,该方法能很好地获取动态信号频率。     

基于极化变换谐振器的远距无芯片RFID湿度传感器设计

提出了一种用于远距离传感的无芯片RFID湿度传感器的设计.设计采用极化变换谐振器,用于减小周围环境对标签响应的影响,提高了传感器的可靠性.传感器标签集成了可实现极化变换的双螺旋条带和四组弯曲哑铃形条带,分别作为湿度传感谐振器和编码谐振器,能够在3.1 GHz～10.6 GHz的超宽带频率范围内产生5个谐振峰.传感谐振器...     

石墨烯的组织性能、改性处理及应用前景

石墨烯因其独特的二维薄片状结构,展现出优异的电学、力学性能,成为材料研究的新热点,带给人们丰富的想象空间。本文从原理、技术特点和组织形貌等方面对比了各种石墨烯的制备技术,总结石墨烯微观结构的表征手段和技术,概括其主要性能。针对当前石墨烯使用的瓶颈问题,阐述了石墨烯非共价键和共价键的改性方法。综述了石墨烯在电池、储能、涂层、医学、传感器、添加剂等方面的应用。最后对石墨烯未来可能的发展方向进行了大胆的预测。     

A novel strain sensor based on graphene composite films with layered structure

The use of graphene for strain sensors has attracted enormous attention due to its prominent mechanical and electrical properties. In this paper, we report on the preparation and characterization of a novel type of strain sensor based on graphene composite films with layered configuration. Highly reliable and sensitive composite films strain sensors based on graphene were produced from solution processed graphene flakes by spray coating method. The layered strain sensor which could sustain a large tensile deformation (25% strain) demonstrated high sensitivity to mechanical strain with gauge factors of 6–35. And the sensitivity of this type of strain sensors can be tuned over a relatively wide range of values by adjusting the deposition parameters. What’s more, the layered composite films are more durable compared with the fragile pure graphene films. In addition the main mechanisms are investigated, resulting in theoretical models which predict very well the observed behavior.     

Graphene-based wearable piezoresistive physical sensors

In the last two decades, wearable piezoresistive physical sensors have attracted tremendous attention due to their broad applications in individual health-monitoring, human–machine interfaces, robotics, sports and therapeutics. Many different nanostructured materials, including nanowires, nanoparticles, nanoribbons, carbon black, carbon nanotubes and graphene, have been explored to construct stretchable piezoresistive sensors on an elastomer substrate. Thanks to its unique two-dimensional geometry, lightweight, flexibility, semi-transparency and outstanding transport and mechanical properties, graphene and its derivatives in particular are considered among the most suitable candidates as wearable sensors. This paper reviews various design strategies established for fabricating flexible, wearable sensors using graphene. The current state-of-the-art developments are discussed of flexible sensors made of 1D fibrous, 2D planar and 3D cellular interconnected graphene architectures for detecting physiological strains, tactile pressures and temperatures. The working mechanisms along with existing applications of flexible sensors are presented. The challenges these sensors are currently facing and potential opportunities for novel applications are revealed to offer new insights into future prospects in this field.     

Graphene: from synthesis to engineering to biosensor applications

Graphene is a fascinating material of recent origin whose first isolation was being made possible through micromechanical cleavage of a graphite crystal. Owing to its fascinating properties, graphene has garnered significant attention in the research community for multiple applications. A number of methods have been employed for the synthesis of single-layer and multi-layer graphene. The extraordinary properties of graphene such as its Hall effect at room temperature, high surface area, tunable bandgap, high charge mobility and excellent electrical, conducting and thermal properties allow for the development of sensors of various types and also opened the doors for its use in nanoelectronics, supercapacitors and batteries. Biological aspects of graphene have also been investigated with particular emphasis on its toxicity and drug delivery. In this review, many of the salient aspects of graphene, such as from synthesis to its applications, primarily focusing on sensor applications which are of current interest, are covered.     

Ultrasensitive Field‐Effect Biosensors Enabled by the Unique Electronic Properties of Graphene

This review provides a critical overview of current developments on nanoelectronic biochemical sensors based on graphene. Composed of a single layer of conjugated carbon atoms, graphene has outstanding high carrier mobility and low intrinsic electrical noise, but a chemically inert surface. Surface functionalization is therefore crucial to unravel graphene sensitivity and selectivity for the detection of targeted analytes. To achieve optimal performance of graphene transistors for biochemical sensing, the tuning of the graphene surface properties via surface functionalization and passivation is highlighted, as well as the tuning of its electrical operation by utilizing multifrequency ambipolar configuration and a high frequency measurement scheme to overcome the Debye screening to achieve low noise and highly sensitive detection. Potential applications and prospectives of ultrasensitive graphene electronic biochemical sensors ranging from environmental monitoring and food safety, healthcare and medical diagnosis, to life science research, are presented as well.     

Progress in miRNA Detection Using Graphene Material–Based Biosensors

MicroRNAs (miRNAs) are short, endogenous, noncoding RNAs that play critical roles in physiologic and pathologic processes and are vital biomarkers for several disease diagnostics and therapeutics. Therefore, rapid, low‐cost, sensitive, and selective detection of miRNAs is of paramount importance and has aroused increasing attention in the field of medical research. Among the various reported miRNA sensors, devices based on graphene and its derivatives, which form functional supramolecular nanoassemblies of π‐conjugated molecules, have been revealed to have great potential due to their extraordinary electrical, chemical, optical, mechanical, and structural properties. This Review critically and comprehensively summarizes the recent progress in miRNA detection based on graphene and its derivative materials, with an emphasis on i) the underlying working principles of these types of sensors, and the unique roles and advantages of graphene materials; ii) state‐of‐the‐art protocols recently developed for high‐performance miRNA sensing, including representative examples; and iii) perspectives and current challenges for graphene sensors. This Review intends to provide readers with a deep understanding of the design and future of miRNA detection devices.     

Review of functionalization,structure and properties of graphene/polymer composite fibers

Fibrous materials usually have good mechanical, heat-resistant, acid-resistant, alkali-resistant and moisture regained properties which originate from its composition, condensed structure and crosslinking styles. However, these materials often lack of good electrical conductivity, flame retardance, anti-static and anti-radiation properties which are desired for varied specific applications. Graphene, as a new emerging nanocarbon material, has some unique properties including superb thermal and electrical conductivity, strong mechanical and anti-corrosive property, extremely high surface area etc. Therefore, graphene has attracted extensive interests in recent years. Upon modification with graphene, fibers exhibit a number of enhanced or new properties such as adsorption performance, anti-bacteria, hydrophobicity and conductivity which are beneficial for broader applications. In this review, the strategies to modify the fibers with graphene and the corresponding effects on the fibers as well as the relevant applications in varied areas were discussed.