Pair Of Fibers Research Articles

The contribution of axial fiber extensibility to the adhesion of viscous capture threads spun by orb-weaving spiders

The viscous capture threads produced by over 4000 species of orb-weaving spiders are formed of regularly spaced aqueous droplets supported by a pair of axial fibers. These threads register increased stickiness when spans of increasing lengths contact a surface, indicating that adhesion is recruited from multiple droplets. This study examined threads produced by five species to test the hypothesis that axial fiber extensibility is crucial for this summation of adhesion. It did so by comparing the stickiness of unstretched threads with threads that had been elongated to reduce the extensibility of their axial fibers. As stretching these threads also increased the distance between their droplets, we measured the stickiness of stretched threads with contact plates whose widths were increased in proportion to the degree of thread elongation. We then accounted for the actual thread elongation achieved for each individual's threads and for differences in the five species' absolute thread extensibility. The results showed that in four species thread extensibility contributed positively to adhesion. For three species, thread extensibility and droplet volume together explained the mean per droplet adhesion of threads. Models based on these three species show that, as threads were elongated, increasing amounts of potential adhesion were lost to diminished axial fiber extensibility. These models indicate that approximately one-third of an unstretched viscous thread's stickiness accrues from the adhesive recruitment made possible by axial fiber extensibility.

Optically induced flow cytometry for continuous microparticle counting and sorting

This paper reports a new microfluidic device capable of performing optically induced flow cytometry (OIFC). This enables it to continuously count and to sort microparticles based on optically induced dielectrophoretic (ODEP) forces. Gravity was used to drive the particles instead of using syringe pumps. The particles were then focused inside a sample channel by the ODEP forces and then passed through a detection region. A pair of optical fibers were embedded into fiber channels to count the number of particles and analyze the particle size in real time. Using 20.9 and 9.7 μm polystyrene microparticles, the average light intensity were about 63.67 and 8.80 units, with a coefficient-of-variation (CV) of 7.46 and 25.57%, respectively. This demonstrated that these two particle sizes could be successfully distinguished. After detecting the number and size of the microparticles, an optically induced dynamic switch (ODS) was used to sort microparticles to downstream fluidic outlets. The ODS used ODEP forces generated by different illumination intensities or optical line widths. The ODS was composed of two virtual electrodes which controlled particle movement in two dimensions. The ODS can successfully sort microparticles with different sizes continuously. The development of the OIFC device is a major advancement in the design of microparticle counting and sorting devices. Applications in future biomedical applications for cell counting and manipulation are envisioned.

Piezoelectricity of chiral polymeric fiber and its application in biomedical engineering

Poly-L-lactic acid (PLLA), which is a type of chiral polymer, exhibits a high shear piezoelectric constant. To realize a higher shear piezoelectric constant, we spun PLLA resin into fibers. We succeeded in controlling the piezoelectric motion of a PLLA fiber by applying a dc voltage and ac voltage, similar to the control of a piezoelectric actuator. On the basis of this experimental result, we designed a catheter using a PLLA fiber (PLLA fiber catheter) and tweezers using a pair of PLLA fibers (PLLA fiber tweezers), controlled by adjusting the applied voltage. Then, using the PLLA fiber tweezers or catheter, we successfully picked up and removed small samples, such as a thrombosis in a blood vessel.

Measurement of steep aspheric surfaces using an anamorphic probe

Synthetic aperture interferometry has been previously proposed as a possible in-process method to measure aspheric form (R. Tomlinson, Appl. Opt.42, 701, 2003.). Preliminary demonstration utilized a scanning probe consisting of a pair of bare single mode fibers to perform source and receive functions. It was found that this probe did not have sufficient numerical aperture (NA) to measure steep surfaces and that simply increasing the NA decreases the light gathering efficiency substantially. In this paper, we introduce supplementary optics to increase the NA, and the light gathering efficiency has been increased by adopting an anamorphic design. A spherical test optic of known form is measured to demonstrate the capability of the new probe design.

一种解调基于3×3方向耦合器的光纤干涉传感器的新技术

Optical fiber interferometric sensors based on [3×3] couplers have been used in many fields. A new technique is proposed to demodulate output signals of this kind of sensors. The technique recovers the signal of interest by fitting coefficients of elliptic (Lissajous) curves between each fiber pair. Different from other approaches, this technique eliminates the dependence on the idealization of [3×3] coupler, provides enhanced tolerance to the variance of photoelectric converters, and is anti-polarization in a certain extent. The main algorithm has been successfully demonstrated both by numerical simulation and experimental result.

Reverse Dispersion Fiber with Depressed Core-index Profile for Dispersion-managed Fiber Pairs

A reverse dispersion fiber (RDF) with depressed core-index profile has been developed successfully using plasma chemical vapor deposition (PCVD) process. The fabricated RDF has a core-effective-area of 45 μm 2 , dispersion of-19.65 ps/nm/km and dispersion slope of -0.132ps/ nm 2 /km while maintaining the low bending induced attenuation and low PMD value. The dispersion-managed pairs, which consisted of RDF and non-zero dispersion shifted fiber with ultra large effective core-area (ULAF), have the ultra low dispersion slope of less than 0.006 ps/ nm 2 /km at the wavelength range of 1530 nm to 1625 nm, and the largest dispersion value is lower than 0.2 ps/nm/ km. Moreover, the attenuation characteristic also shows a remarkable flatness over the broadband wavelength, the attenuation at 1550 nm is only 0.224 dB/km. The dispersion-managed pairs are suitable for large capacity, high bit- rate long-haul wavelength division multiplexing (WDM) transmission system without using dispersion compensation mode.

Homodyne fiber optic backscatter dynamic light scattering

Optical homodyne detection in the backscatter direction is achieved through a pair of collinearly located fibers in a cylindrical probe body. One fiber illuminates the scattering solution while the other fiber provides optical mixing of the backscattered optical field with a local oscillator derived from the Fresnel reflections at the glass interfaces of the sample container. Homodyne detection is possible over a broad range of particle size and sample concentration with a single probe design.

Surface properties of tellurite and fluorotellurite glasses

The surface properties of some freshly cleaved, or polished, quaternary tellurite glasses (TeO2-ZnO-Na2O-Yb2O3and TeO2-ZnO-Na2O-GeO2) and a proposed ternary fluorotellurite core/clad optical fiber pair (TeO2-N a2O-ZnF2) were investigated by means of x-ray photoelectron spectroscopy and chemical durability. Semiquantitative chemical analysis of the x-ray photoelectron spectroscopy spectra of cleaved tungsten-tellurite and fluorotellurite glasses showed good agreement with the batched at.% values when taking into account the effects of processing (e.g., melt fluorine volatilization), and the samples seemed to exhibit negligible hydrolysis. However, spectra of polished surfaces did not yield useful data because of masking of the glass “signal” from organic contamination at the sample surface. The chemical durability of these glasses were studied; specifically, the glass resistance to the attack and the etchability of various acids (aqueous HF, H2SO4, and HCl), alkali (aqueous NaOH), and water at 15, 21, and 60 °C were obtained by simple mass loss experiments and optical microscopy. Based on the appearance of the glass surfaces after immersion in these solutions, aqueous HF was found to be the most promising etchant, however, infrared spectra showed that significant OH was introduced into the glass. Attack of the fluorotellurite glasses was found to proceed at a higher rate in water at 60 °C compared with room temperature, and at both temperatures was shown to be diffusion controlled, with an Arrhenian activation energy estimated as 57 kJ mol−1.

Fiber optic light collection system for scanning-tunneling-microscope-induced light emission

We report a compact light collection scheme suitable for retrofitting a scanning tunneling microscope (STM) for STM-induced light emission experiments. The approach uses a pair of optical fibers with large core diameters and high numerical apertures to maximize light collection efficiency and to moderate the mechanical precision required for alignment. Bench tests indicate that efficiency reduction is almost entirely due to reflective losses at the fiber ends, while losses due to fiber misalignment have virtually been eliminated. Photon-map imaging with nanometer features is demonstrated on a stepped Au(111) surface with signal rates exceeding 10(4) counts/s.

Micro Flow Cytometer Chip Integrated with Micro-Pumps/Micro-Valves for Multi-Wavelength Cell Counting and Sorting

Flow cytometry is a popular technique for counting and sorting of individual cells. This study presents a new chip-based flow cytometer capable of cell injection, counting and switching in an automatic format. The new microfluidic system is also capable of multi-wavelength detection of fluorescence-labeled cells by integrating multiple buried optical fibers within the chip. Instead of using large-scale syringe pumps, this study integrates micro-pumps and micro-valves to automate the entire cell injection and sorting process. By using pneumatic serpentine-shape (S-shape) micro-pumps to drive sample and sheath flows, the developed chip can generate hydrodynamic focusing to allow cells to pass detection regions in sequence. Two pairs of optical fibers are buried and aligned with the microchannels, which can transmit laser light sources with different wavelengths and can collect induced fluorescence signals. The cells labeled with different fluorescent dyes can be excited by the corresponding light source at different wavelengths. The fluorescence signals are then collected by avalanche photodiode (APD) sensors. Finally, a flow switching device composed of three pneumatic micro-valves is used for cell sorting function. Experimental data show that the developed flow cytometer can distinguish specific cells with different dye-labeling from mixed cell samples in one single process. The target cell samples can be also switched into appropriate outlet channels utilizing the proposed microvalve device. The developed microfluidic system is promising for miniature cell-based biomedical applications.

High-precision absolute distance measurement using dual-laser frequency scanned interferometry under realistic conditions

In this paper, we report on new high-precision absolute distance measurements performed with frequency scanned interferometry using a pair of single-mode optical fibers. Absolute distances were determined by counting the interference fringes produced while scanning the frequencies of the two chopped lasers. High-finesse Fabry–Perot interferometers were used to determine frequency changes during scanning. Dual lasers with oppositely scanning directions, combined with a multi-distance-measurement technique previously reported, were used to cancel drift errors and to suppress vibration effects and interference fringe uncertainties. Under realistic conditions, a precision about 0.2 μ m was achieved for a distance of 0.41 m. With a precision that exceeds requirements, the frequency scanned interferometry is a promising high-precision optical alignment technique for International Linear Collider silicon tracker detector.

Elastic Wave Scattering in Porous Unidirectional Fiber-reinforced Composites

Scattering of elastic waves in unidirectional fiber-reinforced porous–matrix composites is studied using novel features of Biot classic model for dynamic poroelasticity. The method of separation of variables along with the appropriate wave field expansions, the pertinent boundary conditions, and the translational addition theorems for cylindrical wave functions are employed to develop a closed-form solution in form of infinite series. The analytical results are illustrated with numerical examples in which a pair of rigid or elastic fibers are insonified by a plane fast compressional or shear wave at end-on/broadside incidence. The effects of incident wave frequency, proximity of the two fibers, fiber material properties and angle of incidence on the far-field backscattered radial and shearing stress amplitudes are examined. Particular attention has been focused on multiple scattering interactions in addition to the slow wave coupling effects which is known to be the primary distinction of the scattering phenomenon in poroelasticity from the classical elastic case. Limiting cases are considered and fair agreements with well-known solutions are established.

Theoretical and experimental study on the optical fiber bundle displacement sensors

The theoretical models of the optical fiber bundle displacement sensors (OFBDS) applicable to various bundle configurations are presented on the basis of a single fiber pair model, which include a summation model, an integral model and a combined model. Upon that, the theoretical characteristics of various bundles are simulated and compared. Experimentally, a double concentric fiber bundle sensor with a carrier amplifier system for verifying the developed models is demonstrated and its sensitivity, linear range, frequency response, resolution and dynamic range are analyzed and calculated. All the theoretical and experimental results are capable of offering quantitative guidance for the design and implementation of fiber bundle sensors.

A Simple Multifunctional Fiber Optic Level/Moisture/Vapor Sensor Using Large-Core Quartz Polymer Fiber Pairs

A simple to manufacture fiber optic transducer that is capable of detecting liquid level, moisture, and vapors based on large-core quartz-polymer optical fiber pairs was realized and tested. The response of the sensor for different transducer form ratios and for a variety of liquids is investigated. It is shown that this simple fiber pair tip can successfully be used to sense vapors of water, acetone, and ethanol. The fiber tip can also be used to monitor the presence of moisture in liquid impregnated materials. Various applications are suggested

Spider Silk: Thousands of Nano-Filaments and Dollops of Sticky Glue

Some spiders use glues while others deploy strands of fine filaments for fixing flies. Recent work has provided new insights into the mechanical properties of these nano-scale ropes.

Generalization of the multiparticle effective field method to random structure matrix composites

In this paper linearly thermoelastic composite media are treated, which consist of a homogeneous matrix containing a statistically homogeneous random set of ellipsoidal uncoated or coated inclusions. Effective properties (such as compliance, thermal expansion, stored energy) as well as the first statistical moments of stresses in the phases are estimated for the general case of nonhomogeneity of the thermoelastic inclusion properties. The micromechanical approach is based on the generalization of the ``multiparticle effective field'' method (MEFM, see [7] for references), previously proposed for the estimation of stress field averages in the phases. The refined version of the MEFM takes into account both the variation of the effective fields acting on each pair of fibers and inhomogeneity of statistical average of stresses inside the inclusions. One considers in detail the connection of the method proposed with numerous related methods. The explicit representations of the effective thermoelastic properties and stress concentration factor are expressed through some building blocks described by numerical solutions for both the one and two inclusions inside the infinite medium subjected to the homogeneous loading at infinity. Just with some additional assumptions (such as an effective field hypothesis) the involved tensors can be expressed through the Green's function, Eshelby tensor and external Eshelby tensor. The dependence of effective properties and stress concentrator factors on the radial distribution function of the inclusion locations is analyzed.

Effect of Inter-Fibre Distance on Energy Transfer in Unidirectional Composites Containing Ultrasonic Waves

Interaction of time harmonic monochromatic anti-plane (SH) waves with a pair of parallel unidirected elastic cylindrical fibres embedded in an unbounded elastic matrix is considered. The classical method of separation of variables along with the appropriate wave field expansions, the pertinent boundary conditions, and the translational addition theorems for cylindrical wave functions are employed to obtain a series solution in terms of Fourier coefficients. The presented development is illustrated with numerical examples in which the fibres are insonified at end-on/broadside incidence for a relatively wide range of nondimensional frequencies. Particular attention has been focused on the effects of lateral fibre spacing on energy transfer between the fibres and matrix. The numerical results reveal that, while inter-fibre scattering (interference) has a small influence on the normalized fibre energies for broadside incidence at all frequencies, it has a considerable impact on the energy distribution for end-on incidence (fibres positioned in the eclipse configuration) at intermediate and high frequencies. The proposed model can complement acousto-ultrasonic (AU) techniques in non-destructive evaluation of unidirectional fibre-reinforced composite materials which is generally hampered by the highly dense concentration of the fibres. Limiting case is considered and fair agreement with a well-known solution is established.

Binaural and cochlear disparities

Binaural auditory neurons exhibit "best delays" (BDs): They are maximally activated at certain acoustic delays between sounds at the two ears and thereby signal spatial sound location. BDs arise from delays internal to the auditory system, but their source is controversial. According to the classic Jeffress model, they reflect pure time delays generated by differences in axonal length between the inputs from the two ears to binaural neurons. However, a relationship has been reported between BDs and the frequency to which binaural neurons are most sensitive (the characteristic frequency), and this relationship is not predicted by the Jeffress model. An alternative hypothesis proposes that binaural neurons derive their input from slightly different places along the two cochleas, which induces BDs by virtue of the slowness of the cochlear traveling wave. To test this hypothesis, we performed a coincidence analysis on spiketrains of pairs of auditory nerve fibers originating from different cochlear locations. In effect, this analysis mimics the processing of phase-locked inputs from each ear by binaural neurons. We find that auditory nerve fibers that innervate different cochlear sites show a maximum number of coincidences when they are delayed relative to each other, and that the optimum delays decrease with characteristic frequency as in binaural neurons. These findings suggest that cochlear disparities make an important contribution to the internal delays observed in binaural neurons.

P5-7: Physiological work-loop style contraction in isolated intact cardiomyocytes

Mechanical conditions acutely affect cardiomyocyte electrophysiology, ion handling, and contractile behaviour, yet the majority of in vitro research is conducted on mechanically unloaded cells. We present a novel force-length clamp (MyoStretcher) that uses a pair of compliant, computer-controlled and piezo-positioned carbon fibers (CF), attached glue-free to opposite cell-ends, to dynamically control the mechanical environment of isolated intact cardiomyocytes. Once CF attachment is established, cells are paced at 2 Hz (physiological saline, 37°C).

High‐dynamic‐range C+L band variable optical attenuator using a titled angle shutter

AbstractA high‐dynamic‐range variable optical attenuator (VOA) using a movable shutter, which moves in a tilted‐angle direction to the collimate fiber pair, is proposed. The VOA operates in the C+L band with the advantages low cost, high dynamic range of more than 50 dB, low insertion loss of 0.8 dB, low wavelength‐dependent loss (WDL), and low polarization‐dependent loss of ±0.4 dB and 0.4 dB, respectively, with attenuation of 50 dB. A compact size of 5.0 × 1.5 × 1.5 cm is obtained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1000–1002, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21547