激光诱导石墨烯柔性可穿戴传感器的研究进展

柔性可穿戴传感器因柔软轻便、延展性强且可用于健康管理、环境监测、食品检测、储能器件等领域而备受关注,基于激光诱导石墨烯的柔性可穿戴传感器克服了传统可穿戴设备的不足,其制备过程具有单步原位制备、绿色环保、低成本等优势,符合新型便携式/可穿戴电子产品向着智能化、微型化、高集成度、柔性化方向发展的趋势,具有良好的发展前景。本文首先阐述了石墨烯的传统制备工艺与激光诱导石墨烯的优缺点;然后分析了碳前体、激光器类型、激光参数、掺杂改性等影响因素对激光诱导石墨烯的结构和性能的影响;接着介绍了激光诱导石墨烯在柔性应变传感器、柔性生理传感器、柔性化学传感器等方面的应用研究;最后,对其应用前景进行了展望。     

高灵敏度网状石墨烯微弱压力传感器的研究北大核心

为了改善微弱压力传感器的灵敏度，利用微结构来产生压阻效应的方法，制备出一种性能优异的压力传感器。研究了三种不同结构的石墨烯压力传感器，并设计和研究了石墨烯压力传感器的版图结构、工艺制备流程和材料表征。最后，对三种不同结构的石墨烯压力传感器进行了灵敏度测试。实验结果表明，网状结构的石墨烯压力传感器具有较高的灵敏度，在低压强下(0～200 Pa)的灵敏度可达到0.303 kPa-1,最低可检测到24.5 Pa的压强。该网状结构的石墨烯压力传感器是一种可以感知微弱压力变化的高性能压力传感器。     

硫掺杂激光诱导石墨烯的制备及抗菌性能

高效抗菌性能的石墨烯基材料的制备具有挑战性.两步激光诱导法被成功用于硫掺杂激光诱导石墨烯(SLIG)的合成,该方法简单可控,并且制备的石墨烯纯度较高.研究了SLIG在胶体溶液中的抗菌性能.通过光密度(OD)法和平板菌落计数法测试了SLIG对大肠杆菌和金黄色葡萄球菌的活性抑制.结果 表明,与激光诱导的石墨烯(LIG)相比...     

基于石墨烯狄拉克点调控和电磁诱导透明的超灵敏太赫兹生物传感器

提出一种由石墨烯和金属铝构成的复合结构的太赫兹超表面生物传感器。超表面由金属铝结构形成类电磁诱导透明谐振，并在铝结构表面通过湿法转移一层石墨烯。通过对石墨烯掺杂蚕丝蛋白来改变石墨烯费米能级，从而改变传感器透射光谱的振幅。实验结果表明，该传感器的检测极限可以达到0.35 ng/mL。利用石墨烯狄拉克点的电磁波调控特性和耦合模型对传感器的工作原理进行分析。在生物医学领域，该生物传感器为微量蛋白的高灵敏检测提供了一种方法。     

基于纳米孔结构的超高压石墨烯压力传感器设计

设计了一种基于纳米孔结构的超高压石墨烯压力传感器。由于氮化硼的六方晶体结构与石墨烯的晶体结构高度相似，该传感器采用氮化硼/石墨烯/氮化硼的石墨烯复合异质敏感薄膜作为压力传感器的敏感材料，利用石墨烯薄膜材料的压阻效应对压力进行检测。为保证传感器在400 MPa的压力载荷下对压力精准的检测，采用数学理论模型计算出不同孔径的纳米孔上石墨烯复合异质薄膜的应变大小，通过有限元仿真软件对石墨烯圆形薄膜的压力进行仿真，得到了圆形薄膜的最优半径。可为超高压石墨烯压力传感的结构设计和性能优化提供一定参考。     

悬浮型石墨烯压力传感阵列的设计与研究

传统的硅压阻式压力传感器存在易受温度影响、断裂韧性较差以及传感节点有限等缺点,因此设计了一种悬浮型阵列结构的石墨烯压力传感器。首先分析了该传感器的结构与原理,然后研究了应变对石墨烯能带结构的影响。最后,建立了顶板-支柱结构的压强放大模型和挠度放大模型。理论与仿真结果表明,压强的放大系数与半径比满足负指数关系,随着支柱底面半径的不断减小,放大系数趋于定值;在集中压力模型中,最大挠度与半径比近似满足线性关系,最大挠度与压强呈三分之一幂次关系。     

基于木材上激光诱导石墨烯集成传感器的研究

木材上激光诱导石墨烯具有环保可降解的优势,被广泛应用于智能木材建筑、家具、植物传感等领域。提出了一种利用木材制备绿色电子传感器的工艺方法,使用中心波长为1070 nm的光纤激光器将木材转化为含有石墨烯的多孔碳结构,方块电阻可达到8Ω·sq^-1。研究表明,激光将木材中的木质素、纤维素与半纤维素中的一部分转化为多孔碳（石墨烯）,压力的变化使得纤维状多孔碳接触或者分离,温度的变化会影响石墨微晶的体积变化,这两者都会影响电阻的变化。制作了灵敏度系数为86.53的压力传感器与电阻温度系数为-0.101%的温度传感器,并制作了集成温度与压力的传感器,传感器满足生活中温度与压力的传感需求,具有广泛的应用前景。     

基于石墨烯压阻效应的压力传感器研究进展

与传统的硅阻型压力传感器、陶瓷型压力传感器相比,石墨烯压力传感器具有测量灵敏度更高、测量范围更广的优点。对几种石墨烯压力传感器的研究进展进行综述。根据制作工艺的不同,将石墨烯压力传感器分为单层型和多层型。根据两大类型,列举最近六种石墨烯压力传感器的基本制作过程和测量范围、检测灵敏度等特性。根据六种石墨烯压力传感器的对比结果,得到单层型与多层型石墨烯压力传感器的不同工作特性及应用环境。针对单层型和多层型石墨烯传感器,分别提出提高性能的可行方案,对此类传感器的实际应用与推广具有一定的指导意义。     

激光诱导碳纳米管制备石墨烯纳米带及其电学性能分析

通过将纳米管解压缩可以很容易地生产石墨烯纳米带,因为碳纳米管结构可以被认为是卷起的石墨烯筒。这是一种特殊的2D石墨结构,具有出色的性能。应用领域广泛,包括晶体管、光学和微波通信设备、生物传感器、化学传感器、电子存储和处理设备以及纳米机电系统和复合材料。通过扫描电子显微镜（SEM）观察薄膜的形貌,通过拉曼光谱法表征石墨烯的性质,并通过半导体参数测量系统测量薄膜的电导率。拉曼光谱表明,通过优化工艺可以增强石墨烯的拉曼特性。碳纳米管制备石墨烯带的两个重要参数是激光能量密度和辐照时间。在这项研究中,通过准分子激光辐照碳纳米管薄膜来生产石墨烯纳米带。实验结果表明,在150 mJ的激光能量下,观察到连接时碳纳米管没有打开。在450 mJ的能量下,可以有效地破坏碳纳米管,并且使其部分地形成石墨烯带。此时,膜的电导率达到最大值。由于蓄热作用,在碳纳米管壁上出现大量的多孔结构。     

石墨烯压力传感器的设计与制作

为了降低电容式石墨烯压力传感器的成本,对石墨烯压力传感器的结构与工艺进行研究,简化加工工艺步骤,设计并制作出石墨烯传感器样片,该传感器样片的灵敏度分为多个区间,最高可达608 MPa~(-1)。首先,将石墨烯溶液制作成纸,利用雕刻工艺将石墨烯纸雕刻成为不同规格的平行叉指图形,并用聚二甲基硅氧烷(PDMS)薄膜覆盖制作成为石墨烯压力传感器。然后,对样片进行静态与动态性能的测试,对测试结果进行对比分析。结果表明该传感器制作工艺简单、成本低廉、性能优良。最后论证了传感器的可行性。     

Rational Design of Soft Yet Elastic Lamellar Graphene Aerogels via Bidirectional Freezing for Ultrasensitive Pressure and Bending Sensors

To enhance the sensitivity of graphene aerogel-based piezoresistive sensors by weakening their compressive strength while keeping their elasticity, lightweight and lamellar graphene aerogels (LGAs) with high elasticity and satisfactory electrical conductance networks are fabricated by bidirectional-freezing of aqueous suspensions of graphene oxide in the presence of small amounts of organic solvents, followed by lyophilizing and thermal annealing. Because of the lamellar structure of the LGA, its compressive strength along the direction perpendicular to the lamellar surface is much lower than those of both isotropic and unidirectionally aligned graphene aerogels with similar apparent densities, leading to an ultrasensitive LGA-based piezoresistive sensor with a high sensitivity of −3.69 kPa⁻¹ and a low detection limit of 0.15 Pa. The ultrahigh sensitivity and low detection limit of LGA-based piezoresistive sensor contribute to detecting subtle pressure at room temperature and in liquid nitrogen with ability to detect dynamic force frequency and sound vibration. Besides, thanks to the fewer junction points between the graphene lamellae, LGAs slices can be integrated as a wide-range and sensitive bending sensor, which can detect arbitrary bending angles from 0° to 180° with a low detection limit of 0.29°, and is efficient in detecting biosignals of wrist pulse and finger bending.     

Bubble‐Decorated Honeycomb‐Like Graphene Film as Ultrahigh Sensitivity Pressure Sensors

Recently, macroporous graphene monoliths (MGMs), with ultralow density and good electrical conductivity, have been considered as excellent pressure sensors due to their excellent elasticity with a rapid rate of recovery. However, MGMs can only exhibit good sensitivity when the strain is higher than 20%, which is undesirable for touch‐type pressure sensors, such as artificial skin. Here, an innovative method for the fabrication of freestanding flexible graphene film with bubbles decorated on honeycomb‐like network is demonstrated. Due to the switching effect depended on “point‐to‐point” and “point‐to‐face” contact modes, the graphene pressure sensor has an ultrahigh sensitivity of 161.6 kPa^?1 at a strain less than 4%, several hundred times higher than most previously reported pressure sensors. Moreover, the graphene pressure sensor can monitor human motions such as finger bending and pulse with a very low operating voltage of 10 mV, which is sufficiently low to allow for powering by energy‐harvesting devices, such as triboelectric generators. Therefore, the high sensitivity, low operating voltage, long cycling life, and large‐scale fabrication of the pressure sensors make it a promising candidate for manufacturing low‐cost artificial skin.     

High‐Performance Dopamine Sensors Based on Whole‐Graphene Solution‐Gated Transistors

Solution‐gated graphene transistors with graphene as both channel and gate electrodes are fabricated for the first time and used as dopamine sensors with the detection limit down to 1 nM, which is three orders of magnitude better than that of conventional electrochemical measurements. The sensing mechanism is attributed to the change of effective gate voltage applied on the transistors induced by the electro‐oxidation of dopamine at the graphene gate electrodes. The interference from glucose, uric acid, and ascorbic acid on the dopamine sensor is characterized. The selectivity of the dopamine sensor is dramatically improved by modifying the gate electrode with a thin Nafion film by solution process. This work paves the way for developing many other biosensors based on the solution‐gated graphene transistors by specifically functionalizing the gate electrodes. Because the devices are mainly made of graphene, they are potentially low cost and ideal for high‐density integration as multifunctional sensor arrays.     

石墨烯压力传感器结构设计与压力敏感特性研究

以石墨烯作为压力传感器敏感材料,Si为基底材料,氮化硼(PN)为石墨烯保护材料,惠斯通测量电桥作为力电变换测量电路,构建了硅基石墨烯压力传感器。通过鼓泡实验法建立传感器的理论模型,分析了传感器的压力与中心形变位移之间的关系,并结合ANSYS软件静力学非线性分析单元,针对所述石墨烯薄膜的挠度形变特性进行了数值解析与有限元仿真。结果表明,石墨烯薄膜压力与挠度形变的理论分析与仿真结果相吻合,这为石墨烯压力传感器提供了结构设计与理论模型基础。     

Lowering Internal Friction of 0D–1D–2D Ternary Nanocomposite‐Based Strain Sensor by Fullerene to Boost the Sensing Performance

The development of strain sensors with both large strain range (>50%) and high gauge factor (>100) is a grand challenge. High sensitivity requires material to perform considerable structural deformation under tiny strain, whereas high stretchability demands structural connection or morphological integrity for materials upon large deformation, yet both features are hard to be achieved in one thin film. A new 0D–1D–2D ternary nanocomposite–based strain sensor is developed that possesses high sensitivity in broad working strain range (gauge factor 2392.9 at 62%), low hysteresis, good linearity, and long‐term durability. The skin‐mountable strain sensor, fabricated through one‐step screen‐printing process, is made of 1D silver nanowire offering high electrical conductivity, 2D graphene oxide offering brittle layered structure, and 0D fullerene offering lubricity. The fullerene constitutes a critical component that lowers the friction between graphene oxide–based layers and facilitates the sliding between adjacent layers without hurting the brittle nature of the nanocomposite film. When stretching, layer slippage induced by fullerene can accommodate partial applied stress and boost the strain, while cracks originating and propagating in the brittle nanocomposite film ensure large resistance change over the whole working strain range. Such high comprehensive performance renders the strain sensor applicable to full‐spectrum human motion detection.     

Synchronous Growth of High‐Quality Bilayer Bernal Graphene: From Hexagonal Single‐Crystal Domains to Wafer‐Scale Homogeneous Films

The precise control of the domain structure, layer thickness, and stacking order of graphene has attracted intense interest because of its great potential for nanoelectronics applications. Much effort has been devoted to synthesize semiconducting Bernal (AB)‐stacked bilayer graphene because of its tunable band structure and electronic properties that are unavailable to single‐layer graphene. However, fast growth of large‐scale bilayer graphene sheets with a high AB‐stacking ratio and high mobility on copper poses a tremendous challenge, which has to overcome the self‐limiting effect. This study reports a low‐cost but facile method to rapidly synthesize bilayer Bernal graphene by atmospheric pressure chemical vapor deposition using polystyrene as the feedstock. The bilayer graphene grains and continuous film obtained are of high quality and exhibit field‐effect hole mobilities as high as 5700 and 2200 cm² V^?1 s^?1 at room temperature, respectively. In addition, a synchronous growth mechanism of bilayer graphene is revealed by monitoring the growth process, resulting in a high surface coverage of nearly 100% for a near‐perfect AB‐stacking order. This new synthesis route is significant for industrial application of bilayer graphene and investigation of the growth mechanism of graphene by the chemical vapor deposition process.     

Oxygen‐Free Highly Conductive Graphene Papers

Graphene papers have a potential to overcome the gap from nanoscale graphene to real macroscale applications of graphene. A unique process for preparation of highly conductive graphene thin paper by means of Ar⁺ ion irradiation of graphene oxide (GO) papers, with carbon/oxygen ratio reduced to 100:1, is presented. The composition of graphene paper in terms of carbon/oxygen ratio and in terms of types of individual oxygen‐containing groups is monitored throughout the process. Angle‐resolved high resolution X‐ray photoelectron spectroscopy helps to investigate the depth profile of carbon and oxygen within reduced GO paper. C/O ratios over 100 on the surface and 40 in bulk material are observed. In order to bring insight to the processes of oxygen removal from GO paper by low energy Ar⁺ ion bombardment, the gases released during the irradiation are analyzed by mass spectroscopy. It is proven that Ar⁺ ion beam can be applied as a technique for fabrication of highly reduced graphene papers with high conductivities. Such highly conductive graphene papers have great potential to be used in application for construction of microelectronic and sensor devices.     

MEMS硅膜电容式气象压力传感器的研制

基于MEMS的电容式压力传感器以其低成本高性能在气象测量中有着广阔的应用前景。利用ANSYS软件模拟接触式电容压力传感器的工作状态,得到硅膜的形变和应力分布状况。制作流程采用简单标准的工艺:利用KOH各向异性腐蚀进行硅片大面积、大深度腐蚀减薄,分析了其浓度配比对硅面平整度特性的影响,采用阳极键合形成真空腔,试验反应离子深刻蚀形成硅膜的效果。芯片测试结果表明方案可行。     

Large‐Area Ultrathin Graphene Films by Single‐Step Marangoni Self‐Assembly for Highly Sensitive Strain Sensing Application

Promoted by the demand for wearable devices, graphene has been proved to be a promising material for potential applications in flexible and highly sensitive strain sensors. However, low sensitivity and complex processing of graphene retard the development toward the practical applications. Here, an environment‐friendly and cost‐effective method to fabricate large‐area ultrathin graphene films is proposed for highly sensitive flexible strain sensor. The assembled graphene films are derived rapidly at the liquid/air interface by Marangoni effect and the area can be scaled up. These graphene‐based strain sensors exhibit extremely high sensitivity with gauge factor of 1037 at 2% strain, which represents the highest value for graphene platelets at this small deformation so far. This simple fabrication for strain sensors with highly sensitive performance of strain sensor makes it a novel approach to applications in electronic skin, wearable sensors, and health monitoring platforms.