Fiber Cantilever Research Articles

非对称光纤悬臂探头的驱动优化研究

非对称光纤悬臂探头的驱动优化研究

非对称光纤悬臂探头的驱动优化研究

非对称光纤悬臂探头的驱动优化研究

非对称光纤悬臂探头的驱动优化研究

非对称光纤悬臂探头的驱动优化研究

Fiber-optic nonlinear endomicroscopy with focus scanning by using shape memory alloy actuation

A miniature fiber optic endomicroscope with built-in dynamic focus scanning capability is developed for the first time for 3-D two-photon fluorescence (TPF) imaging of biological samples. Fast 2-D lateral beam scanning is realized by resonantly vibrating a double-clad fiber cantilever with a tubular piezoactuator. Slow axial scanning is achieved by moving the distal end of the imaging probe with an extremely compact electrically driven shape memory alloy (SMA). The 10-mm-long SMA allows 150-μm contractions with a driving voltage varying only from 50 to 100 mV. The response of the SMA contraction with the applied voltage is nonlinear, but repeatable and can be accurately calibrated. Depth-resolved imaging of acriflavine-stained biological tissues and unstained white paper with the endomicroscope is performed, and the results demonstrate the feasibility of 3-D nonlinear optical imaging with the SMA-based scanning fiber-optic endomicroscope.

Semi-resonant operation of a fiber-cantilever piezotube scanner for stable optical coherence tomography endoscope imaging

A forward-view optical coherence tomography (OCT) scanning catheter has been developed based on a fiber-cantilever piezotube scanner by using a semi-resonant scan strategy for a better scan performance. A compact endoscope catheter was fabricated by using a tubular piezoelectric actuator with quartered electrodes in combination with a resonant fiber cantilever. A cantilever weight was attached to the fiber cantilever to reduce the resonance frequency down to 63 Hz, well in the desirable range for Fourier-domain OCT. The resonant-cantilever scanner was driven at semi-resonance frequencies that were well out of the resonance peak but within a range of partial resonance. This driving strategy has been found to minimize the phase difference between the two scan axes for a better scan stability against environmental perturbations as well as for a driving simplicity. By driving the two axes at slightly different frequencies, a low-order Lissajous pattern has been obtained for a 2D area scan. 3D OCT images have been successfully acquired in an acquisition time of 1.56 seconds for a tomogram volume of 2.2 × 2.2 × 2.1 mm3. They were reconstructed without any scan calibration by extracting the scan timing from the image data. In addition, it has been found that the Lissajous scan strategy provides a means to compensate the relative axial motion of a sample for a correct imaged morphology.

Note: Aligned deposition and modal characterization of micron and submicron poly(methyl methacyrlate) fiber cantilevers

Polymeric micro-/nanofibers are finding increasing use as sensors for novel applications. Here, we demonstrate the ability to deposit an array of poly(methyl methacyrlate) fibers with micron and submicron diameters in aligned configurations on customized piezoelectric shakers. Using lateral motion of an atomic force microscope tip, fibers are broken to obtain fiber cantilevers of high aspect ratio (length/diameter > 20). The resonant frequencies of fabricated microfiber cantilevers are experimentally measured using a laser Doppler vibrometer. An average Young's modulus of 3.5 GPa and quality factor of 20 were estimated from the experimentally obtained frequency responses.

Two-dimensional scanning realized by an asymmetry fiber cantilever driven by single piezo bender actuator for optical coherence tomography

We develop a fiber based probe that is capable of two-dimensional scanning applicable in optical coherence tomography (OCT). Based on the resonance of the fiber cantilever with asymmetry structure which has two distinguished resonant frequencies in orthogonal directions, Lissajous pattern is produced suitable for two-dimensional scanning upon a sample. Orthogonal resonances of the fiber cantilever are simultaneously excited by single piezo bender actuator with one driving signal consisting of two components corresponding to above-mentioned two resonant frequencies. By integrating a backward-placed two-dimensional position sensitive detector (PSD) into the probe, real-time lateral position of the scanning pattern is registered simultaneously for image reconstruction. Dynamical characteristics of the fiber cantilever are experimentally studied with special consideration on factors determining the resolution of the scanning pattern, including frequency and amplitude ratios between two components of the driving signal and fetching duration used for an en face image. With the developed probe implemented in our established OCT system, en face OCT images of typical samples are obtained with satisfying resolution and contrast, demonstrating the feasibility of such fiber cantilever with asymmetry structure for realizing two dimensional scanning by single actuator, potentially applicable to endoscopic OCT imaging.

Micromanipulators Comprising Optical Fiber Cantilevers

We propose an optically driven micromanipulator which operates on the basis of the photothermal effect and possesses some interesting characteristics, such as non-generation of magnetic noise and the ability of receiving energy remotely. The manipulator is composed of three optical fiber cantilevers which are cut in a bevel shape and painted with a photo-absorbent material attached on the angled edge of the fiber. The photothermal effect is used for moving the manipulator when the incident beam is introduced at the end of the optical fiber. The manipulator can manipulate samples and move them to arbitrary places in three-dimensional space.

The plastic optical fiber cantilever beam as a force sensor

AbstractThis study reports use of inexpensive intensity‐based plastic optical fiber (POF) in the form of cantilever beam to monitor the force. The cantilever consists of POF surface bonded on the surface of metal beams viz. spring steel (SS) and mild steel (MS) and subjected to force. The performance of the force sensor is evaluated during macro‐bending caused because of the deflection of the beam by applied force. Experimentally obtained detector output of POF, which could be measured with negligible hysteresis is compared with finite element analysis in the range between 0.0098 and 19.613 N. The reproducibility of the sensor is observed in the limit of ±1%. The proposed sensor can replace stain gauge load cell to certain extent in some applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1020–1023, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24217

A novel approach to the sensing of liquid density using a plastic optical fibre cantileverbeam

This article reports for the first time the use of a plastic optical fibre (POF)cantilever beam to measure the density of a liquid. The sensor is based on theArchimedes buoyancy principle. The sensor consists of a POF bonded on the surface ofa metal beam in the form of a cantilever configuration, and at the free end ofthe beam a displacer is attached. Due to the apparent loss of the true weight ofthe displacer there is a deflection in the cantilever beam, which causes macrobending in the POF. The loss of intensity due to macro bending of the POF is ameasure of the density of the liquid under test. The variation of weight loss withthe density of different liquids showed that the weight loss is proportional todensity. This sensor is capable of detecting the weight loss with respect to theirdensities even for liquids having close values of density like distilled water, tapwater, and milk of various brands. The resolution of the sensor is observed to be1.1 mg cm−3.

Two-Axis Temperature-Insensitive Accelerometer Based on Multicore Fiber Bragg Gratings

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We report a compact two-dimensional accelerometer based upon a simple fiber cantilever constructed from a short length of multicore optical fiber. Two-axis measurement is demonstrated up to 3 kHz. Differential measurement between fiber Bragg gratings written in the multicore fiber provides temperature-insensitive measurements. </para>

Electromechanical measurements of electric field-induced displacements of fibers

In this paper we report on a development of a new method for measurements of electric field-induced displacements in a cylindrical geometry (optical fiber with the deposited piezoelectric film). The measurement setup is based on a commercially available Fotonic Sensor MTI 2000 (MTI Inc.). Major disadvantages of measurement by standard techniques (e.g., interferometry) such as low reflectivity, high roughness of the coating resulting in poor fringe quality, and big displacement range are successfully avoided using a special configuration of an optical probe and a sample. The method allows performing investigations of electromechanically induced vibrations in a broad frequency range (from 0 up to 150 kHz) and various combinations of ac and dc voltages. The capabilities of the proposed method are validated by strain measurements of an optical fiber cantilever beam covered by Pb(Zr,Ti)O(3) thick film.

1306 埋め込み新型光ファイバセンサを用いた振動・ひずみ同時測定(J14-2 知的材料・構造システム(2) 計測・モニタリングI,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

We have developed fiber optic strain and vibration sensors (FOSVS) suited for health monitoring of structures. A fiber optic gap sensor made of multi-mode fibers, broad-band light, two photo detectors and an FBG filter were used to compose the sensor system. The gap sensor was composed of a cantilever fiber and a reflector fiber. The axial strain of the sensor was measured from the reflected interfered signal. The amplitude of the transmitted signal through the reflector fiber was used to measure the transverse vibration of the cantilever fiber. In the present study, the sensors were embedded in epoxy plates and cantilever vibration tests were conducted. From the experimental and theoretical results, it appeared that the embedded FOSVS in specimens could measure dynamic strain and vibration of a vibrating cantilever plate simultaneously. From these results, it can be concluded that the FOSVS sensor has practical capability of simultaneous measurement of internal strain and vibration of materials.

Fluorescence correlation spectroscopy at 100 nM concentrations using near‐field scanning optical microscopic (NSOM) geometries and highly diffracting force sensing fiber probes

AbstractA tapered cantilevered optical fiber probe is introduced for fluorescence correlation spectroscopy (FCS). The probe has an aperture that is coated with metal and its dimension can be very well defined. Its design is based on cantilevered near‐field optical fiber probes that allow for on‐line atomic force feedback. This permits unprecedented stability in FCS measurements. Even such probes that have large diameters are below the cutoff wavelength of light propagation in optical fibers. Such large diameter probes produce bright spots of light that are highly diffracting. Therefore, only the fluence of light very close to the surface of the glass probe aperture is sufficient to exhibit a high probability of fluorescence excitation. From the results presented in this paper the z extent of such probes seems comparable to what can be obtained from prism‐based evanescent wave methods, but with much more flexibility and including force sensing capability. In agreement with theoretical results on prism evanescent field‐based excitation, it is shown that even with large xy dimensions for the fiber probes in this paper, fluorescence correlation spectra from 100 nM fluorophore concentrations can be recorded. This is 10 times larger than the concentrations generally required for conventional confocal FCS. The results suggest that such an approach has considerable potential for applications of FCS in membrane, near‐membrane, solution, and even within‐cell environments. The latter is achieved through atomic force feedback controlled penetration of tapered cantilevered metal‐coated glass fibers into cells, and this is also reported in this paper.

Extensible elastica solutions on the large deflection of fiber cantilever with circular wavy crimp. II. Classification of equilibrium configurations

The types of equilibrium shapes in the extensible elastica solutions of planar deflection of two-element crimped fiber cantilever with circular wavy crimp were classified for one end clamped boundary under concentrated, inclined and dead tip load. Material property of the fiber was also regarded linear elastic, while crimp was described as a combination of semicircular arcs smoothly connected with each other having constant curvature of all the same magnitude and alternative sign. Investigating the mathematical features of the previously obtained solutions shows that the possibility and variety of multiple equilibrium shapes originates from the following two reasons: the existence of Case 1/Case 2 type transformation, and the mathematical features of Case 1 type transformation. In two-element crimped fiber, there exist four different choices for Case1/Case2 type transformation. Regarding Case 2-Case 2 type equilibrium shape as the default and most probable one, other three types of equilibrium shape can be regarded as multiple equilibrium shapes. Moreover, Case 1 type transformation itself may lead to multiple configurations due to the possibility of the contra-flexure point after bending while Case 2 type transformation doesn’t allow such characteristics. Case 1-Case 1 type equilibrium shape shows maximum varieties in shape, while Case 2-Case 1 and Case 1-Case 2 type shapes occasionally leads to the identical results with different choice of the sign. Tables and shapes in each configuration were also presented.

Near-field scanning optical microscopy based nanostructuring of glass

Nanofabrication, at lateral resolutions beyond the capability of conventional optical lithography techniques, is demonstrated here. Femtosecond laser was used in conjunction with Near-field Scanning Optical Microscopes (NSOMs) to nanostructure thin metal films. Also, the possibility of using these nanostructured metal films as masks to effectively transfer the pattern to the underlying substrate by wet etching process is shown. Two different optical nearfiled processing schemes were studied for near-field nanostructuring. In the first scheme, local field enhancement in the near-field of a scanning probe microscope (SPM) probe tip irradiated with femtosecond laser pulses was utilized (apertureless NSOM mode) and as a second approach, femtosecond laser beam was spatially confined by cantilevered NSOM fiber tip (apertured NOSM mode). The minimized heat- and shock-affected areas introduced during ultrafast laser based machining process, allows processing of even high conductivity thin metal films with minimized formation of any interfacial compounds between the metal films and the underlying substrate. Potential applications of this method may be in the fields of nanolithography, nanofluidics, nanoscale chemical and gas sensors, high-density data storage, nano-opto-electronics, as well as biotechnology related applications.

Bi-Stable Composites with Piezoelectric Actuators for Shape Change

Unsymmetrical carbon fibre/epoxy composites with bonded piezoelectric fibre actuators were investigated as a means to shape change, or morph, composite structures. A carbon fibre cantilever was examined along with its response to applied strains (from piezoelectric actuators), with emphasis on the characterisation of shape/deflection and the reproducibility of the shape/deflection of the structure.

Automated Two-Axes Optical Fiber Alignment Using Grayscale Technology

In this paper, we report a new method for actuating an optical fiber in two axes. This device enables in package active alignment of an optical fiber towards reducing the time and cost of optoelectronic packaging by eliminating the need for expensive and slow macroalignment machines. Opposing comb-drive actuators with integrated three-dimensional (3-D) wedges (fabricated using grayscale technology) create a dynamic v-groove to alter the horizontal and vertical alignment of an optical fiber cantilever. All structural components are fabricated in silicon using a single lithography and dry-etching step, making the system conducive to batch fabrication, an essential element to minimize the cost of including in-package alignment capabilities. Actuation of a cleaved fiber tip greater than 30 mum in each direction is demonstrated, with automated fiber alignment times on the order of 10s, comparable to those achieved using macroalignment systems. Alignment tolerances are held below 1.25 mum over a 20-by-20-mum actuation area for the first time. The influences of alignment target location, actuation parameters, and alignment algorithm on total alignment time are also presented

Microfluidic flow rate detection based on integrated optical fiber cantilever

We demonstrate an integrated microfluidic flow sensor with ultra-wide dynamic range, suitable for high throughput applications such as flow cytometry and particle sorting/counting. A fiber-tip cantilever transduces flow rates to optical signal readout, and we demonstrate a dynamic range from 0 to 1500 microL min(-1) for operation in water. Fiber-optic sensor alignment is guided by preformed microfluidic channels, and the dynamic range can be adjusted in a one-step chemical etch. An overall non-linear response is attributed to the far-field angular distribution of single-mode fiber output.

Proximal Probes Based Nanorobotic Drawing of Polymer Micro/Nanofibers

This paper proposes a nanorobotic fiber fabrication method which uses proximal probes to draw polymer fibers down to few hundred nanometers in diameter and several hundred micrometers in length. Using proximal probes such as Atomic Force Microscope (AFM) and Scanning Tunneling Microscope (STM) or glass micropipettes, liquid polymers dissolved in a solvent are drawn. During drawing, the solvent evaporates in real-time which solidifies the fiber. Controlling the drawn fibers trajectory and solidification in three-dimensions (3-D), suspended fibers, fiber cantilevers, custom 3-D fibers, and fiber networks, are proposed to be fabricated. Poly(methyl methacrylate) (PMMA) polymer dissolved in chlorobenzene is used to form a variety of suspended polymer fibers with diameters from few microns to 200nm. Fabrication of crossed and linear networks of fibers is also demonstrated. Viscoelastic modeling of polymer fiber drawing is realized using a finite element method to test the significance of the drawing speed and velocity profile on the extensional behavior of the drawn fiber. Since the mechanical properties of the drawn micro/nanofibers could vary from the bulk polymer material significantly, mechanical characterization of suspended fibers using an AFM and a Nanoindenter setup is proposed. Extending this technique to a variety of nonconductive and electroactive polymer fibers, many novel applications in micro/nanoscale sensors, actuators, fibrillar structures, and optical and electronic devices would become possible