长距离分布式光纤传感技术研究进展

分布式光纤传感技术是光纤传感领域的重要组成部分,具有以下突出优势:无需在光纤上制作传感器,传感光纤集传感与传输于一体,可实现远距离、大范围的传感与组网;可连续感知光纤传输路径上每一点的温度、应变、振动等物理参量的空间分布和变化信息,单根光纤上能获得多达数万点的传感信息.由于在长距离连续传感方面具有不可替代的优势,分布式光纤传感技术在周界安防、石油电力、大型结构等领域的安全监控方面具有非常广阔的应用前景.本文主要介绍电子科技大学光纤传感与器件研究团队在长距离分布式光纤静(布里渊光时域分析仪)、动(相位敏感型光时域反射仪)态参量传感技术取得的研究进展,包括基础与应用研究两个方面.     

Synthesis of Graphene and Its Applications: A Review

Graphene, one-atom-thick planar sheet of carbon atoms densely packed in a honeycomb crystal lattice, has grabbed appreciable attention due to its exceptional electronic and optoelectronic properties. The reported properties and applications of this two-dimensional form of carbon structure have opened up new opportunities for the future devices and systems. Although graphene is known as one of the best electronic materials, synthesizing single sheet of graphene has been less explored. This review article aims to present an overview of the advancement of research in graphene, in the area of synthesis, properties and applications, such as field emission, sensors, electronics, and energy. Wherever applicable, the limitations of present knowledgebase and future research directions have also been highlighted.     

阵列波导光栅解调的准分布式光纤光栅传感器

从理论上和实验上研究了一种操作简单、响应速度快,价格低廉和高分辨率的基于阵列波导光栅(AWG)的准分布式光纤布拉格光栅(FBG)传感器.该传感系统采用了阵列波导光栅双通道强度解调技术对光纤光栅的布拉格波长和温度进行精确的解调.实验结果表明,该系统对宽带宽光纤光栅的布拉格波长和温度解调均具有高线性度,考虑系统稳定性及光纤布拉格光栅之间的串扰影响,波长测量精度仍可达2 pm,温度测量精度优于0.2℃.     

Novel materials for bioanalytical and biomedical applications: Environmental response and binding/release capabilities of amphiphilic hydrogels with shape‐persistent dendritic junctions

The binding and release capabilities of a hydrogel series, constructed of hydrophilic poly(ethylene glycol) segments and hydrophobic dendritic junctions [poly (benzyl ether)s], are evaluated in aqueous media. The environmental response of the amphiphilic networks is also tested in water at three pH values: 1.5, 7.0, and 10.1. The highest swelling ratio is observed under acidic conditions and varies between 3.7 and 6.5, depending on the crosslinking density and dendrimer generation. Gel specimens with embedded indicators react within 3–6 s with a clear color switch to the change in the pH of the surrounding medium. The experiments with model anionic and cationic indicators and stains show that the hydrogels have basic interiors. The gel binding capabilities depend on the water solubility of the substrate and on the size of the incorporated dendritic fragments. Model release studies have been performed at 37 °C and pHs 1.5, 7.0, and 10.1. The observed phenomena are explained by the transformations in the structure and charge that both the networks and the model compounds undergo with the changes in the pH of the aqueous medium. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4017–4029, 2005     

A PEGylated Fluorescent Turn‐On Sensor for Detecting Fluoride Ions in Totally Aqueous Media and Its Imaging in Live Cells

Owing to the considerable significance of fluoride anions for health and environmental issues, it is of great importance to develop methods that can rapidly, sensitively and selectively detect the fluoride anion in aqueous media and biological samples. Herein, we demonstrate a robust fluorescent turn‐on sensor for detecting the fluoride ion in a totally aqueous solution. In this study, a biocompatible hydrophilic polymer poly(ethylene glycol) (PEG) is incorporated into the sensing system to ensure water solubility and to enhance biocompatibility. tert‐Butyldiphenylsilyl (TBDPS) groups were then covalently introduced onto the fluorescein moiety, which effectively quenched the fluorescence of the sensor. Upon addition of fluoride ion, the selective fluoride‐mediated cleavage of the Si? O bond leads to the recovery of the fluorescein moiety, resulting in a dramatic increase in fluorescence intensity under visible light excitation. The sensor is responsive and highly selective for the fluoride anion over other common anions; it also exhibits a very low detection limit of 19 ppb. In addition, this sensor is operative in some real samples such as running water, urine, and serum and can accurately detect fluoride ions in these samples. The cytotoxicity of the sensor was determined to be Grade I toxicity according to United States Pharmacopoeia and ISO 10993‐5, suggesting the very low cytotoxicity of the sensor. Moreover, it was found that the senor could be readily internalized by both HeLa and L929 cells and the sensor could be utilized to track fluoride level changes inside the cells.     

Advances in nucleic acid architectures for electrochemical sensing

Nucleic acid–based electrochemical sensors are ideally suited to the detection of molecular targets for which enzymatic detection or direct electrochemical oxidation – reduction reactions are not possible. Moreover, the versatility of nucleic acids in their ability to bind a great variety of target types, from small molecules to single-entity mesoscopic targets, makes them attractive receptors for the development of electrochemical biosensors. In this brief opinion piece, we discuss field advances from the past two years. We hope the works highlighted here will inspire the community to pursue creative designs enabling the detection of larger and more complex targets with a specific focus on analytical validation and translation into preclinical or clinical applications.     

Pd Uptake and H2S Sensing by an Amphoteric Metal–Organic Framework with a Soft Core and Rigid Side Arms

Molecular components of opposite character are often incorporated within a single system, with a rigid core and flexible side arms being a common design choice. Herein, molecule L has been designed and prepared featuring the reverse design, with rigid side arms (arylalkynyl) serving to calibrate the mobility of the flexible polyether links in the core. Crystallization of this molecule with Pb^II ions led to a dynamic metal–organic framework (MOF) system that not only exhibits dramatic, reversible single‐crystal‐to‐single‐crystal transformations, but combines distinct donor and acceptor characteristics, allowing for substantial uptake of PdCl₂ and colorimetric sensing of H₂S in water.     

Simultaneous In Situ Quantification of Two Cellular Lipid Pools Using Orthogonal Fluorescent Sensors

Lipids regulate a wide range of biological activities. Since their local concentrations are tightly controlled in a spatiotemporally specific manner, the simultaneous quantification of multiple lipids is essential for elucidation of the complex mechanisms of biological regulation. Here, we report a new method for the simultaneous in situ quantification of two lipid pools in mammalian cells using orthogonal fluorescent sensors. The sensors were prepared by incorporating two environmentally sensitive fluorophores with minimal spectral overlap separately into engineered lipid‐binding proteins. Dual ratiometric analysis of imaging data allowed accurate, spatiotemporally resolved quantification of two different lipids on the same leaflet of the plasma membrane or a single lipid on two opposite leaflets of the plasma membrane of live mammalian cells. This new imaging technology should serve as a powerful tool for systems‐level investigation of lipid‐mediated cell signaling and regulation.     

Direct In Situ Nitridation of Nanostructured Metal Oxide Deposited Semiconductor Interfaces: Tuning the Response of Reversibly Interacting Sensor Sites

Metal‐oxide nanostructure‐decorated extrinsic semiconductor interfaces modified through in situ nitridation greatly expand the range of sensor interface response. Select metal‐oxide sites, deposited to an n‐type nanopore‐coated microporous interface, direct a dominant electron‐transduction process for reversible chemical sensing, which minimizes chemical‐bond formation. The oxides are modified to decrease their Lewis acidity through a weak interaction to form metal oxynitride sites. Conductometric and X‐ray photoelectron spectroscopy measurements demonstrate that in situ treatment changes the reversible interaction with the analytes NH₃ and NO. The sensor range is extended, which creates a distinct new family of responses determined by the Lewis acidity/basicity of a given analyte relative to that of the nanostructures chosen to decorate the interface. The analyte response, broadened in a substantial and predictable way by nitridation, is explained by the recently developing inverse hard/soft acid/base model (IHSAB) of reversible electron transduction.     

Evidence for Electron Transfer between Graphene and Non-Covalently Bound π-Systems

Hybridizing graphene and molecules possess a high potential for developing materials for new applications. However, new methods to characterize such hybrids must be developed. Herein, the wet-chemical non-covalent functionalization of graphene with cationic π-systems is presented and the interaction between graphene and the molecules is characterized in detail. A series of tricationic benzimidazolium salts with various steric demand and counterions was synthesized, characterized and used for the fabrication of graphene hybrids. Subsequently, the doping effects were studied. The molecules are adsorbed onto graphene and studied by Raman spectroscopy, XPS as well as ToF-SIMS. The charged π-systems show a p-doping effect on the underlying graphene. Consequently, the tricationic molecules are reduced through a partial electron transfer process from graphene, a process which is accompanied by the loss of counterions. DFT calculations support this hypothesis and the strong p-doping could be confirmed in fabricated monolayer graphene/hybrid FET devices. The results are the basis to develop sensor applications, which are based on analyte/molecule interactions and effects on doping.