Developments in microscale and nanoscale sensors for biomedical sensing

The widespread use of point of care testing in biomedical and clinical applications is a major aim of the electrochemical field. A large number of groups are working on lab-on-a-chip systems or sensor arrays which are underpinned by electrochemical detection methodologies. Miniaturized transducers have the potential to be adopted in such systems for diagnosis of a range of diseases in both clinical and nonclinical settings. In this review, we will present the current trends and state of the art for a selection of miniaturized sensing elements (microelectrodes, nanoelectrodes, and field-effect transistors) and provide an impression of current technologies, their associated performance characteristics, and also considering the major barriers to adoption and how they might be surmounted in future so these technologies can fulfil their early promise.     

Fe-C合金膜光纤腐蚀传感器传感规律研究

利用PVD溅射镀以及PVD与电镀复合两种方法在光纤纤芯上制备了不同厚度的Fe-C合金膜,对其进行X-射线衍射分析,所制膜层晶体结构类型与普通碳钢基本一致.通过将镀膜光纤放入不同浓度的HNO3溶液中以及埋入混凝土结构中,进行了腐蚀实验.结果表明:在低浓度的腐蚀溶液中,不同厚度的Fe-C合金膜会从外到内被均匀地腐蚀掉,输出光功率会在腐蚀末期有一个急剧的增大现象;在高浓度的腐蚀溶液中,Fe-C合金膜会在各个局部产生裂纹,膜层被一块一块地腐蚀掉;输出光功率整体趋势增大,但并没有特别急剧的增大现象;混凝土试块中的腐蚀实验中,输出光功率的变化复杂多变,但整体趋势还是一个增大的过程.     

反相电极聚合物定向耦合电光开关的优化设计

为了消除单节电极定向耦合电光开关的工艺误差对器件性能的不良影响,应用耦合模理论、电光调制理论、保角变换及镜像法,优化设计了一种两节交替反相电极聚合物定向耦合电光开关.模拟结果表明,该器件具有良好的开关性能:在1 550 nm的工作波长下,器件耦合区的长度为4 753.5 μm,交叉态电压为1.22 V,直通态电压为2.65 V,插入损耗小于2.21 dB,串扰小于-30 dB.通过微调状态电压,可以很容易地消除工艺误差对器件性能产生的不良影响.本文方法的设计结果与光束传播法的仿真结果符合得很好.     

A Noninvasive, on Wafer Method to Determine the Intrinsic Stress of a Polymer Layer

The method described in this paper allows an investigator to determine the intrinsic stress of a polymer layer in a way that does not result in damage to devices or test structures. The method requires that a small area of the polymer be released from the substrate to form a diaphragm. The diaphragm is stimulated with acoustic white noise and the diaphragm movement is monitored with a laser vibrometer. The first few resonance frequencies of the diaphragm are obtained using a laser vibrometer and then those frequencies are used to calculate the membrane intrinsic bi-axial tension.     

One-stage fabrication of sub-micron hydrophilic microchannels on PDMS

A sub-micron hydrophilic microchannel was fabricated on poly(dimethylsiloxane) (PDMS) in one step using vacuum ultraviolet light (VUV) lithography in vacuum. The topographies and properties of the irradiated PDMS surface were characterized and analyzed by atomic force microscopy (AFM), and the chemical composition changes on VUV-treated PDMS analyzed by X-ray photoelectron spectroscopy (XPS). The hydrophilic stability of irradiated PDMS surface was studied by static water contact angle. As demonstrated, the hydrophilicity on surface of PDMS microchannel can be kept for a longer term even three months after the treatment.     

The use of fluoropolymers to protect semiconductor materials

Fluoropolymers are the materials of choice for many materials integrity management applications within the microelectronics industry. This brief overview discusses common types of fluoropolymers and the stringent requirements of semiconductor-processing environments. Fluoropolymers are used in a wide variety of such fluid and device handling applications because they provide a unique combination of toughness, purity, and chemical resistance.     

Temperature Sensitivity Control and Mechanical Stress Effect of Boron-Doped Long-Period Fiber Gratings

We will present in this work the quantitative analysis of the relationship between the doping concentrations of GeO 2 and B 2 O 3 in the core and cladding regions and the temperature sensitivity of the resonance wavelength shift in long-period fiber gratings (LPFGs). Based on this analysis, the temperature sensitivity was suppressed and enhanced to 0.002 nm/C and 0.28 nm/C, respectively. We will also discuss the effect of the residual mechanical stress on the optical and mechanical properties of LPFGs. In particular, we will present the measurement results of the dependence of the refractive index change and mechanical strength on the residual mechanical stress in the boron-doped fibers with depressed clad and matched clad.     

Facile fabrication of pomponlike microarchitectures of lanthanum molybdate via an ultrasound route

Pomponlike La₂(MoO₄)₃ microstructures assembled with single-crystalline nanoflakes have been facilely fabricated via a surfactant-assisted ultrasound route for the first time. Various synthesis conditions were examined, such as the surfactant concentration, the molecular structure of surfactants, and the pH value. The obtained pomponlike microstructures were characterized by X-ray diffraction (XRD), (field-emission) scanning electron microscopy [(FE)SEM], transmission electron microscopy (TEM), and nitrogen adsorption/desorption isotherms. It has been revealed that a minimum concentration of sodium dodecylsulfate (SDS) was required for the formation of pomponlike La₂(MoO₄)₃ microstructures. When the SDS concentration is above 0.02 mol L⁻¹, the pomponlike microstructures become more perfect, and the size is also increased with the increasing SDS concentration. Under the same sonication, similar pomponlike microstructures were obtained when a cationic surfactant, cetyltrimethyl ammonium bromide (CTAB), was used instead of the anionic surfactant SDS, indicating that the hydrophobic alkyl chains are an important factor for the formation of the pomponlike La₂(MoO₄)₃ microstructures. It is also found that the pomponlike La₂(MoO₄)₃ microstructures can only be obtained within an optimal pH range of 8.0–9.0 under sonication. Based on TEM, Fourier transform infrared spectroscopy (FT-IR) and solubilization experiment, a formation mechanism of pomponlike La₂(MoO₄)₃ microstructures was proposed, in which the collaborative action of surfactants and sonication plays a key role. Furthermore, the porosity of the pomponlike La₂(MoO₄)₃ microstructures were discussed.     

崇启大桥钢箱梁试验段制造工艺技术研究

本文基于崇启大桥主桥钢箱梁梁段制造工艺参数采集的需要,对试验段的制造工艺技术进行了探讨与研究。     

采用施工图预算控制工程造价的探讨

本文在介绍施工图预算概念及其主要内容的基础上,阐述了采用施工图预算控制工程造价的步骤和特点,并对改革趋势进行了分析。