Adaptive optical array receivers for detection of surface acoustic waves

Adaptive interferometric detection systems based on two-wave mixing in photorefractive crystals have been configured as distributed optical receivers. The spatial distribution of the detection laser power on the sample surface is controlled by use of phase gratings and amplitude masks. The responses of point, line, array, and chirped optical receivers to propagating surface acoustic waves (SAW's) are discussed theoretically and demonstrated experimentally. It is shown that by use of different object beam footprints it is possible to configure adaptive holographic SAW receivers that are either broadband or narrow band and that are preferentially sensitive to SAW's propagating in given directions. The receivers also allow for the distribution of laser power over the sample, eliminating the excessive heating or surface damage that can occur in some materials when high power, point-focused, detection lasers are used.     

Laser surface modification of titanium substrate for pulsed laser deposition of highly adherent hydroxyapatite

Biomedical implant devices made out of titanium and its alloys are benefited by a modified surface or a bioactive coating to enhance bone bonding ability and to function effectively in vivo for the intended period of time. In this respect hydroxyapatite coating developed through pulsed laser deposition is a promising approach. Since the success of the bioactive ceramic coated implant depends mainly on the substrate-coating strength; an attempt has been made to produce micro patterned surface structure on titanium substrate for adherent hydroxyapatite coating. A pulsed Nd-YAG laser beam (355 nm) with 10 Hz repetition rate was used for surface treatment of titanium as well as hydroxyapatite deposition. The unfocussed laser beam was used to modify the substrate surface with 500–18,000 laser pulses while keeping the polished substrate in water. Hydroxyapatite deposition was done in a vacuum deposition chamber at 400°C with the focused laser beam under 1 × 10⁻³ mbar oxygen pressure. Deposits were analyzed to understand the physico-chemical, morphological and mechanical characteristics. The obtained substrate and coating surface morphology indicates that laser treatment method can provide controlled micro-topography. Scratch test analysis and microindentation hardness values of coating on laser treated substrate indicate higher mechanical adhesion with respect to coatings on untreated substrates.     

Focused ion beam-fabricated Au micro/nanostructures used as a surface enhanced Raman scattering-active substrate for trace detection of molecules and influenza virus

The focused ion beam (FIB) technique was used to precisely fabricate patterned Au micro/nanostructures (fibAu). The effects of surface enhanced Raman scattering (SERS) on the fibAu samples were investigated by adjusting the geometrical, dimensional, and spacing factors. The SERS mechanism was evaluated using low-concentration rhodamine 6G (R6G) molecules, physically adsorbed or suspended on/within the micro/nanostructures. The results indicated that for detecting R6G molecules, hexagon-like micro/nanostructures induced a higher electromagnetic mechanism (EM) due to the availability of multiple edges and small curvature. By decreasing the dimensions from 300 to 150 nm, the laser-focused area contained an increasing number of micro/nanostructures and therefore intensified the excitation of SERS signals. Moreover, with an optimized geometry and dimensions of the micro/nanostructures, the relative intensity/surface area value reached a maximum as the spacing was 22 nm. An exponential decrease was found as the spacing was increased, which most probably resulted from the loss of EM. The spacing between the micro/nanostructures upon the fibAu was consequently regarded as the dominant factor for the detection of R6G molecules. By taking an optimized fibAu to detect low-concentration influenza virus, the amino acids from the outermost surface of the virus can be well distinguished through the SERS mechanism.     

Influence of substrate surface conditions on the deposition and spreading of molten droplets

This paper reports the finding of the role of substrate surface chemistry on the interaction between the molten droplets (splats) and solid substrates in thermal spray coating. The substrate surfaces were modified by thermal treatments to grow specific types of oxide and hydroxide layers on the surface. It was found that water released from the dehydration of surface hydroxide triggered by the impact of the droplets provoked splat fragmentation and splashing, resulting in the poor splat-substrate bonding. Although this finding is used to address the question of the nature and the influence of surface adsorbates on the splat formation and morphology in thermal spray coating, it can be applied to other technologies and material processes involving the contact between the molten droplets and metal surfaces.     

Combined enhanced fluorescence and label-free biomolecular detection with a photonic crystal surface

A 2D photonic crystal surface with a different period in each lateral direction is demonstrated to detect biomolecules using two distinct sensing modalities. The sensing mechanisms both rely on the generation of a resonant reflection peak at one of two specific wavelengths, depending on the polarization of light that is incident on the photonic crystal. One polarization results in a resonant reflection peak in the visible spectrum to coincide with the excitation wavelength of a fluorophore, while the orthogonal polarization results in a resonant reflection peak at an infrared wavelength which is used for label-free detection of adsorbed biomolecules. The photonic crystal resonance for fluorescence excitation causes enhanced near fields at the structure surface, resulting in increased signal from fluorophores within 100 nm of the device surface. Label-free detection is performed by illuminating the photonic crystal with white light and monitoring shifts in the peak reflected wavelength of the infrared resonance with a high-resolution imaging detection instrument. Rigorous coupled-wave analysis was used to determine optimal dimensions for the photonic crystal structure, and devices were fabricated using a polymer-based nanoreplica molding approach. Fluorescence-based and label-free detection were demonstrated using arrays of spots of dye-conjugated streptavidin. Quantification of the fluorescent signal showed that the fluorescence output from protein spots on the photonic crystal was increased by up to a factor of 35, and deposited spots were also imaged in the label-free detection mode.     

Noncompetitive phage anti-immunocomplex real-time polymerase chain reaction for sensitive detection of small molecules

Immuno polymerase chain reaction (IPCR) is an analytical technology based on the excellent affinity and specificity of antibodies combined with the powerful signal amplification of polymerase chain reaction (PCR), providing superior sensitivity to classical immunoassays. Here we present a novel type of IPCR termed phage anti-immunocomplex assay real-time PCR (PHAIA-PCR) for the detection of small molecules. Our method utilizes a phage anti-immunocomplex assay (PHAIA) technology in which a short peptide loop displayed on the surface of the M13 bacteriophage binds specifically to the antibody-analyte complex, allowing the noncompetitive detection of small analytes. The phagemid DNA encoding this peptide can be amplified by PCR, and thus, this method eliminates hapten functionalization or bioconjugation of a DNA template while providing improved sensitivity. As a proof of concept, two PHAIA-PCRs were developed for the detection of 3-phenoxybenzoic acid, a major urinary metabolite of some pyrethroid insecticides, and molinate, a herbicide implicated in fish kills. Our results demonstrate that phage DNA can be a versatile material for IPCR development, enabling universal amplification when the common element of the phagemid is targeted or specific amplification when the real time PCR probe is designed to anneal the DNA encoding the peptide. The PHAIA-PCRs proved to be 10-fold more sensitive than conventional PHAIA and significantly faster using magnetic beads for rapid separation of reactants. The assay was validated with both agricultural drain water and human urine samples, showing its robustness for rapid monitoring of human exposure or environmental contamination.     

Single-stranded DNA binding protein-assisted fluorescence polarization aptamer assay for detection of small molecules

Here, we describe a new fluorescence polarization aptamer assay (FPAA) strategy which is based on the use of the single-stranded DNA binding (SSB) protein from Escherichia coli as a strong FP signal enhancer tool. This approach relied on the unique ability of the SSB protein to bind the nucleic acid aptamer in its free state but not in its target-bound folded one. Such a feature was exploited by using the antiadenosine (Ade)-DNA aptamer (Apt-A) as a model functional nucleic acid. Two fluorophores (fluorescein and Texas Red) were introduced into different sites of Apt-A to design a dozen fluorescent tracers. In the absence of the Ade target, the binding of the labeled aptamers to SSB governed a very high fluorescence anisotropy increase (in the 0.130-0.200 range) as the consequence of (i) the large global diffusion difference between the free and SSB-bound tracers and (ii) the restricted movement of the dye in the SSB-bound state. When the analyte was introduced into the reaction system, the formation of the folded tertiary structure of the Ade-Apt-A complex triggered the release of the labeled nucleic acids from the protein, leading to a strong decrease in the fluorescence anisotropy. The key factors involved in the fluorescence anisotropy change were considered through the development of a competitive displacement model, and the optimal tracer candidate was selected for the Ade assay under buffer and realistic (diluted human serum) conditions. The SSB-assisted principle was found to operate also with another aptamer system, i.e., the antiargininamide DNA aptamer, and a different biosensing configuration, i.e., the sandwich-like design, suggesting the broad usefulness of the present approach. This sensing platform allowed generation of a fluorescence anisotropy signal for aptamer probes which did not operate under the direct format and greatly improved the assay response relative to that of the most previously reported small target FPAA.     

Sensitive detection of small molecules by competitive immunomagnetic-proximity ligation assay

A novel detection method of small molecules, competitive immunomagnetic-proximity ligation assay (CIPLA), was developed and described in this report. Through the proximity effect caused by special proximity probes we prepared, small molecules can be detected using only one monoclonal antibody. CIPLA overcomes the obstacle that the proximity ligation assay (PLA) cannot be used in small molecular detection, as two antibodies are unable to combine to one small molecule due to its small molecular structure. Two small molecular compounds, clenbuterol (CLE) and ractopamine (RAC), were selected as targets for CIPLA. The limit of detection (LOD) reached 0.01 ng mL(-1), which was 10-50-fold lower than ELISA. With 5 orders of magnitude of the dynamic range achieved, the excellent sensitivity and broad dynamic range of CIPLA are noted. It can be applied widely in the sensitive detection of many other small molecular materials such as pesticides, additives in food, drugs, and biological samples, which have great significance in both theoretical and practical aspects.     

水下小孔径阵列远程目标检测方法研究

匹配滤波器频域自适应线谱增强方法是一种基于递归算法的非线性滤波技术,它大大提高了匹配滤波器的检测性能.针对当前该技术使用窄带信号作为发射信号存在可利用的带宽有限,不能充分发挥自适应线谱增强器性能的问题,文章提出将该技术与宽带信号相结合来检测远程目标.仿真显示,该方法在低信噪比条件下获得了较高的信噪比增益和检测概率.海试...     

Optimized angle scanning method for array sample detection in surface plasmon resonance biosensor

An optimized angle scanning method is presented for array sample detection in a surface plasmon resonance biosensor. It provides a way to find the optimal rotation axis in the prism to resolve the drifting problem of the light incidence point on samples in the plane prism-coupling mode. The detection of array samples can be achieved by the translation of the prism along a particular direction. The validity of this method is theoretically analyzed and demonstrated by experiments.     

TiO2 deposition on the surface of activated fluoropolymer substrate

Anatase-structured TiO₂ films were deposited on a commercial fluorinated polymer (FEP) with a treated surface, by means of a sol-gel dip-coating technique. Two different curing temperatures were investigated and the film microstructures were characterized by X-ray diffraction, atomic force microscopy and scanning electron microscopy analyses. The prepared samples presented very high performances in terms of photocatalytic activities, analyzed by the degradation of an organic dye in a liquid medium, and of bactericidal activities, tested on Staphylococcus aureus (S. aureus, a Gram positive bacterium) and Escherichia coli (E. coli, a Gram negative bacterium).     

Implantable photonic crystal for reflection-based optical sensing of biodegradation

Biodegradable inverse opal (IoPPC) was synthesized from a multifunctional carboxylic acid and polyols by colloidal crystal templating. The IoPPC was prepared by infiltration of the monomer solution into interparticle voids of silica colloidal crystal template, polycondensation of the infiltrated film, and removal of the template. The synthesized IoPPC was characterized by infrared absorption, X-ray diffraction measurements, differential scanning calorimetry, and thermogravimetry/mass spectrometry analysis. In order to clarify the effect of biodegradation on the inverse opal structure and the optical reflection property, the IoPPC was implanted in subcutaneous tissue of the lower back of three mice (ICR, 10 weeks, female). After the 2 weeks implantation, fragmented samples were harvested from the implant location and investigated by scanning electron microscope observations and optical reflection measurements. It was found that the reflection peak for the harvested samples decayed from that for the sample without implantation. Such a spectral change is considered to be attributed to the deterioration of the regularity of the inverse opal structures through biodegradation. The finding of this study will serve in the development of reflection-based sensing in various biomedical applications. The in vivo degradation experiment was approved by the committee on animal experiments of School of Science and Engineering, Kinki University.

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Design of an optical interconnect for photonic backplane applications

A compact alignment-tolerant interconnect has been developed for use within a prototype modulator-based free-space photonic backplane. The interconnect design encompasses several unique features. Microlens arrays are used, and several beams share each microlens by clustering the optical input-output in a small field about the optical axis of each lens. For simplifying the layout, the optical input and output of each smart-pixel array are clustered separately, thereby allowing a Fourier plane patterned-mirror array to be used in the beam-combination optics. This allows a suitable balance between high interconnection densities and reasonable optical relay distances between adjacent boards to be achieved. The primary advantages of this scheme are the simplicity of the optical design and its alignability, making it ideally suited for high-density interconnection applications.     

Diffusion dynamics of small molecules from mesoporous silicon films by real-time optical interferometry

Time-dependent laser reflectometry measurements are presented as a means to rigorously characterize analyte diffusion dynamics of small molecules from mesoporous silicon (PSi) films for drug delivery and membrane physics applications. Calculations based on inclusion of a spatially and temporally dependent solute concentration profile in a one-dimensional Fickian diffusion flow model are performed to determine the diffusion coefficients for the selected prototypical polar species, sucrose (340 Da), exiting from PSi films. The diffusion properties of the molecules depend on both PSi pore size and film thickness. For films with average pore diameters between 10-30?nm and film thicknesses between 300-900?nm, the sucrose diffusion coefficient can be tuned between approximately 100 and 550?μm2/s. Extensions of the real-time measurement and modeling approach for determining the diffusivity of small molecules that strongly interact with and corrode the internal surfaces of PSi films are also discussed.     

Rapid and sensitive detection of respiratory virus molecular signatures using a silver nanorod array SERS substrate

A spectroscopic assay based on surface enhanced Raman scattering (SERS) using silver nanorod array substrates has been developed that allows for rapid detection of trace levels of viruses with a high degree of sensitivity and specificity. This novel SERS assay can detect spectral differences between viruses, viral strains, and viruses with gene deletions in biological media. The method provides rapid diagnostics for detection and characterization of viruses generating reproducible spectra without viral manipulation.     

Mass amplifying probe for sensitive fluorescence anisotropy detection of small molecules in complex biological samples

Fluorescence anisotropy (FA) is a reliable and excellent choice for fluorescence sensing. One of the key factors influencing the FA value for any molecule is the molar mass of the molecule being measured. As a result, the FA method with functional nucleic acid aptamers has been limited to macromolecules such as proteins and is generally not applicable for the analysis of small molecules because their molecular masses are relatively too small to produce observable FA value changes. We report here a molecular mass amplifying strategy to construct anisotropy aptamer probes for small molecules. The probe is designed in such a way that only when a target molecule binds to the probe does it activate its binding ability to an anisotropy amplifier (a high molecular mass molecule such as protein), thus significantly increasing the molecular mass and FA value of the probe/target complex. Specifically, a mass amplifying probe (MAP) consists of a targeting aptamer domain against a target molecule and molecular mass amplifying aptamer domain for the amplifier protein. The probe is initially rendered inactive by a small blocking strand partially complementary to both target aptamer and amplifier protein aptamer so that the mass amplifying aptamer domain would not bind to the amplifier protein unless the probe has been activated by the target. In this way, we prepared two probes that constitute a target (ATP and cocaine respectively) aptamer, a thrombin (as the mass amplifier) aptamer, and a fluorophore. Both probes worked well against their corresponding small molecule targets, and the detection limits for ATP and cocaine were 0.5 μM and 0.8 μM, respectively. More importantly, because FA is less affected by environmental interferences, ATP in cell media and cocaine in urine were directly detected without any tedious sample pretreatment. Our results established that our molecular mass amplifying strategy can be used to design aptamer probes for rapid, sensitive, and selective detection of small molecules by means of FA in complex biological samples.     

光学面形绝对检测方法发展综述

详细介绍了三平（球）面互检法、双球面法、旋转平均法、平移差分法（伪剪切干涉法）、奇偶函数 法、随机球法和旋转平移法等光学面形绝对检测方法的测量原理,针对不同方法简述了国内外绝对检测技术的 发展动态,并对比了不同绝对检测方法的适用领域以及存在相应的技术限制。从物理实现和算法两方面对绝对 检测技术的未来发展趋势进行展望,提出了通过提高外部机械结构精度来增加面型绝对检测精度,分析了深度 神经网络算法与计算光学成像技术两种方法在绝对检测过程中的优势,并提出通过将两种方法与绝对检测技术 相结合可进一步提高光学面形的绝对检测精度,为绝对检测相关领域的研究提供有益参考。     

A large-scale-oriented ZnO rod array grown on a glass substrate via an in situ deposition method and its photoconductivity

In order to obtain oriented nanostructured materials for nanoelectronic/microelectronic device applications via a simple method, a study on the preparation of oriented ZnO was carried out. The experimental results indicated that large-scale-oriented ZnO rod arrays on glass substrates via an in situ deposition approach can be obtained. The I–V examination of the oriented ZnO rod arrays film showed that the photocurrent increased of about two orders of magnitude after white light exposure.     

Effects of substrate parameters on structure and optical properties of ZnO thin films fabricated by pulsed laser deposition

Highly oriented zinc oxide thin films have been grown on quartz, Si (1 1 1) and sapphire substrates by pulsed laser deposition (PLD). The effect of temperature and substrate parameter on structural and optical properties of ZnO thin films has been characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), optical transmission spectra and PL spectra. The experimental results show that the best crystalline thin films grown on different substrate with hexagonal wurtzite structure were achieved at growth temperature 400–500 °C. The growth temperature of ZnO thin film deposited on Si (1 1 1) substrate is lower than that of sapphire and quartz. The band gaps are increasing from 3.2 to 3.31 eV for ZnO thin film fabricated on quartz substrate at growth temperature from 100 to 600 °C. The crystalline quality and UV emission of ZnO thin film grown on sapphire substrate are significantly higher than those of other ZnO thin films grown on different substrates.