Actuators Based on Photomechanical Polymer

2006 ◽  
Vol 18 (6) ◽  
pp. 684-691 ◽  
Author(s):  
LaQuieta Huey ◽  
◽  
Sergey S. Sarkisov ◽  
Michael J. Curley ◽  
Grigory Adamovsky ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Resonance Frequency ◽  
Polyvinylidene Fluoride ◽  
Laser Excitation ◽  
Slow Motion ◽  
Full Agreement ◽  
Physical Mechanisms ◽  
Photonic Switch ◽  
Adaptive Mirror ◽  
Photomechanical Effect

New light-driven actuators based on films of polymer polyvinylidene fluoride are described. The actuators employ the photomechanical bending of the polymer film caused by low power (10mW and less) laser radiation. The photomechanical effect combines various physical mechanisms, such as anisotropic thermal expansion, converse piezoelectric mechanism along with photovoltaic and pyroelectric ones, while the mechanism of thermal expansion is dominant for slow motion. Mechanical vibrations of the strips of the photomechanical polymer were observed with periodic pulsed laser excitation. The resonance frequency is inversely proportional to the square of the length of the strip, in full agreement with the theory. Resonance frequency measurements were used to determine the modulus of elasticity of the films, which was close to 3.0x109Pa. Two possible applications were discussed: photonic switch and adaptive mirror. The proposed actuators have a potential of being used as the components of future light-driven micro/nano systems.

Photomechanical effect in films of polyvinylidene fluoride

2004 ◽  
Vol 85 (14) ◽  
pp. 2747-2749 ◽  
Author(s):  
Sergey S. Sarkisov ◽  
Michael J. Curley ◽  
Aisha Fields ◽  
Sergey S. Sarkisov ◽  
Grigory Adamovsky
Keyword(s):  
Polyvinylidene Fluoride ◽  
Photomechanical Effect

scholarly journals Unusual Breathing Behavior of Optically Excited Barium Titanate Nanocrystals

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 365
Author(s):  
Jiecheng Diao ◽  
Mathew Cherukara ◽  
Ross Harder ◽  
Xiaojing Huang ◽  
Fucai Zhang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Barium Titanate ◽  
Free Electron Laser ◽  
Laser Excitation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Contacts ◽  
Diffraction Peaks ◽  
Diffraction Patterns ◽  
Transfer Direction

Coherent X-ray diffraction patterns were recorded by using an X-ray free-electron laser to illuminate barium titanate nanocrystals as a function of time delay after laser excitation. Rather than seeing any significant thermal expansion effects, the diffraction peaks were found to move perpendicular to the momentum transfer direction. This suggests a laser driven rotation of the crystal lattice, which is delayed by the aggregated state of the crystals. Internal deformations associated with crystal contacts were also observed.

scholarly journals Stress Transients Generated by Excimer-Laser Irradiation of Polyimide

1992 ◽  
Vol 285 ◽  
Author(s):  
A. D. Zweig ◽  
V. Venugopalan ◽  
T. F. Deutsch
Keyword(s):  
Thermal Decomposition ◽  
Laser Irradiation ◽  
Excimer Laser ◽  
Polyvinylidene Fluoride ◽  
Laser Wavelength ◽  
Stress Generation ◽  
Physical Mechanisms ◽  
Gas Dynamic ◽  
Excimer Laser Irradiation ◽  
193 Nm

ABSTRACTWe measure the stress transients resulting from pulsed excimer laser irradiation of polyimide at 351, 308, 248 and 193 nm, using thin (9 μm) piezoelectric PVDF (polyvinylidene fluoride) films. We find that fluences between 3·10−3 and 102 J/cm2 generate peak stresses between 104 and 109 Pa. Further, the results show three ranges of fluence where different physical mechanisms mediate the stress generation. In the lowest range of fluence, subsurface thermal decomposition (for λ = 351 and 308 nm) and photodecomposition (for λ = 248 and 193 nm) govern the generation of the observed stresses. At higher fluences we identify two regimes, independent of laser wavelength, where the gas dynamic expansion of the ablation products and plasma formation and expansion, are responsible for the generated stresses.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

Strain analysis with nanometer resolution using a conventional transmission electron microsopy technique: electron diffraction contrast imaging revisited

1995 ◽  
Vol 53 ◽  
pp. 168-169
Author(s):  
Koenraad G F Janssens ◽  
Omer Van der Biest ◽  
Jan Vanhellemont ◽  
Herman E Maes ◽  
Robert Hull
Keyword(s):  
Electron Diffraction ◽  
Strain Field ◽  
Elastic Strain ◽  
Strain Analysis ◽  
Local Strain ◽  
Contrast Imaging ◽  
Strain Characterization ◽  
Physical Mechanisms ◽  
Diffraction Contrast ◽  
Transmission Electron

There is a growing need for elastic strain characterization techniques with submicrometer resolution in several engineering technologies. In advanced material science and engineering the quantitative knowledge of elastic strain, e.g. at small particles or fibers in reinforced composite materials, can lead to a better understanding of the underlying physical mechanisms and thus to an optimization of material production processes. In advanced semiconductor processing and technology, the current size of micro-electronic devices requires an increasing effort in the analysis and characterization of localized strain. More than 30 years have passed since electron diffraction contrast imaging (EDCI) was used for the first time to analyse the local strain field in and around small coherent precipitates1. In later stages the same technique was used to identify straight dislocations by simulating the EDCI contrast resulting from the strain field of a dislocation and comparing it with experimental observations. Since then the technique was developed further by a small number of researchers, most of whom programmed their own dedicated algorithms to solve the problem of EDCI image simulation for the particular problem they were studying at the time.

Current Issues: Advanced Digital Technology for Supervising Graduate Clinicians

2010 ◽  
Vol 20 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Glenn Tellis ◽  
Lori Cimino ◽  
Jennifer Alberti
Keyword(s):  
Real Time ◽  
Digital Technology ◽  
Clinical Training ◽  
State Of The Art ◽  
Clinical Skills ◽  
Slow Motion ◽  
Video Capture ◽  
Microsoft Excel ◽  
Clinical Supervisors ◽  
Training And Supervision

Abstract The purpose of this article is to provide clinical supervisors with information pertaining to state-of-the-art clinic observation technology. We use a novel video-capture technology, the Landro Play Analyzer, to supervise clinical sessions as well as to train students to improve their clinical skills. We can observe four clinical sessions simultaneously from a central observation center. In addition, speech samples can be analyzed in real-time; saved on a CD, DVD, or flash/jump drive; viewed in slow motion; paused; and analyzed with Microsoft Excel. Procedures for applying the technology for clinical training and supervision will be discussed.

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