Eberhard Manske, Thomas Fröhlich and Suren Vasilyan
Practical means of generation and calibration of the small precision forces in static and dynamic regimes around 1 Hz by the usage of radiation pressure effect from 1 W continuous wave visible (diode) laser light is presented. The additive effect of the transfer of photon momentum, caused by non-overlapping multiply reflecting laser beam locked within quasi-passive and/or active macroscopic cavity system, is employed. The effective laser power (partially trapped experimentally) is amplified such that the optically generated forces are increased from hundreds of pN up to sub-µN level. The results presented in this paper should be seen as a means for extending the edge of practically verifiable lower limits of SI-traceable force metrology.
DOI
Showing posts with label Measurement Science and Technology. Show all posts
Showing posts with label Measurement Science and Technology. Show all posts
Tuesday, July 23, 2019
Wednesday, January 20, 2016
Atomic force microscopy combined with optical tweezers (AFM/OT)
F Pierini, K Zembrzycki, P Nakielski, S Pawłowska and T A Kowalewski
The role of mechanical properties is essential to understand molecular, biological materials, and nanostructures dynamics and interaction processes. Atomic force microscopy (AFM) is the most commonly used method of direct force evaluation, but due to its technical limitations this single probe technique is unable to detect forces with femtonewton resolution. In this paper we present the development of a combined atomic force microscopy and optical tweezers (AFM/OT) instrument. The focused laser beam, on which optical tweezers are based, provides us with the ability to manipulate small dielectric objects and to use it as a high spatial and temporal resolution displacement and force sensor in the same AFM scanning zone. We demonstrate the possibility to develop a combined instrument with high potential in nanomechanics, molecules manipulation and biological studies. AFM/OT equipment is described and characterized by studying the ability to trap dielectric objects and quantifying the detectable and applicable forces. Finally, optical tweezers calibration methods and instrument applications are given.
DOI
The role of mechanical properties is essential to understand molecular, biological materials, and nanostructures dynamics and interaction processes. Atomic force microscopy (AFM) is the most commonly used method of direct force evaluation, but due to its technical limitations this single probe technique is unable to detect forces with femtonewton resolution. In this paper we present the development of a combined atomic force microscopy and optical tweezers (AFM/OT) instrument. The focused laser beam, on which optical tweezers are based, provides us with the ability to manipulate small dielectric objects and to use it as a high spatial and temporal resolution displacement and force sensor in the same AFM scanning zone. We demonstrate the possibility to develop a combined instrument with high potential in nanomechanics, molecules manipulation and biological studies. AFM/OT equipment is described and characterized by studying the ability to trap dielectric objects and quantifying the detectable and applicable forces. Finally, optical tweezers calibration methods and instrument applications are given.
DOI
Thursday, February 19, 2015
Measurement of the gold–gold bond rupture force at 4 K in a single-atom chain using photon-momentum-based force calibration
D T Smith and J R Pratt
We present instrumentation and methodology for simultaneously measuring force and displacement at the atomic scale at 4 K. The technique, which uses a macroscopic cantilever as a force sensor and high-resolution, high-stability fiber-optic interferometers for displacement measurement, is particularly well-suited to making accurate, traceable measurements of force and displacement in nanometer- and atomic-scale mechanical deformation experiments. The technique emphasizes accurate co-location of force and displacement measurement and measures cantilever stiffness at the contact point in situ at 4 K using photon momentum. We present preliminary results of measurements made of the force required to rupture a single atomic bond in a gold single-atom chain formed between a gold flat and a gold tip. Finally, we discuss the possible use of the gold–gold bond rupture force as an intrinsic force calibration value for forces near 1 nN.
DOI
We present instrumentation and methodology for simultaneously measuring force and displacement at the atomic scale at 4 K. The technique, which uses a macroscopic cantilever as a force sensor and high-resolution, high-stability fiber-optic interferometers for displacement measurement, is particularly well-suited to making accurate, traceable measurements of force and displacement in nanometer- and atomic-scale mechanical deformation experiments. The technique emphasizes accurate co-location of force and displacement measurement and measures cantilever stiffness at the contact point in situ at 4 K using photon momentum. We present preliminary results of measurements made of the force required to rupture a single atomic bond in a gold single-atom chain formed between a gold flat and a gold tip. Finally, we discuss the possible use of the gold–gold bond rupture force as an intrinsic force calibration value for forces near 1 nN.
DOI
Saturday, May 19, 2012
Characterization of Bessel beams generated by polymeric microaxicons
F Merola, S Coppola, V Vespini, S Grilli and P Ferraro
We present a quick, simple and accurate digital holographic characterization of the Bessel beams produced by polymeric microaxicons. This technique allows the numerical reconstruction of both intensity and phase of the beam at whichever point starting from a single acquired hologram. From these data, it is possible to go back to the axicon structure, and to gather information about their characteristics. In particular, the focal length and the depth of focus of the axicon lens are experimentally measured, and the full width at half maximum of the beam is obtained too. The depth of focus, very large for a Bessel beam with respect to a Gaussian one, is successfully exploited for optical trapping of micrometric objects.
DOI
We present a quick, simple and accurate digital holographic characterization of the Bessel beams produced by polymeric microaxicons. This technique allows the numerical reconstruction of both intensity and phase of the beam at whichever point starting from a single acquired hologram. From these data, it is possible to go back to the axicon structure, and to gather information about their characteristics. In particular, the focal length and the depth of focus of the axicon lens are experimentally measured, and the full width at half maximum of the beam is obtained too. The depth of focus, very large for a Bessel beam with respect to a Gaussian one, is successfully exploited for optical trapping of micrometric objects.
DOI
Tuesday, September 20, 2011
Epigenetic inheritance of elongated phenotypes between generations revealed by individual-cell-based direct observation
Yuichi Wakamoto and Kenji Yasuda
A cellular phenotype is considered to be determined not only by genetic information but also by convoluted information on past states of a cell and its ancestors, i.e. hysteresis. This 'hysteretic effect' forms the basis of epigenetic phenomena. To understand these phenomena by which cells transmit certain phenotypes to descendants, it is necessary to observe individual cells and compare the phenotypes of each between generations under stringently controlled environmental conditions. We, therefore, did an individual-cell-based differential assay using Escherichia coli as a model organism. We observed normal-sized isolated cells change into elongated phenotypes, and subsequently measured the transmission of their characteristics between generations. This change occurred when the final length of the normal cells exceeded their cell-length boundary, i.e., 10 µm with 5% probability. Once a cell became elongated, it divided unequally, producing two daughter cells; one was elongated and the other was normal. The elongated daughter transmitted the elongated phenotype to one lineage of the descendants by repeating unequal cell divisions with an average interdivision time half that of the normal phenotype, whereas the normal daughter retained normal phenotypic characteristics. The results suggest one possible non-genetic inheritance of cellular characteristics where phenotypic differences can only be inherited by geometrical information, independent of specific gene regulation.
DOI
A cellular phenotype is considered to be determined not only by genetic information but also by convoluted information on past states of a cell and its ancestors, i.e. hysteresis. This 'hysteretic effect' forms the basis of epigenetic phenomena. To understand these phenomena by which cells transmit certain phenotypes to descendants, it is necessary to observe individual cells and compare the phenotypes of each between generations under stringently controlled environmental conditions. We, therefore, did an individual-cell-based differential assay using Escherichia coli as a model organism. We observed normal-sized isolated cells change into elongated phenotypes, and subsequently measured the transmission of their characteristics between generations. This change occurred when the final length of the normal cells exceeded their cell-length boundary, i.e., 10 µm with 5% probability. Once a cell became elongated, it divided unequally, producing two daughter cells; one was elongated and the other was normal. The elongated daughter transmitted the elongated phenotype to one lineage of the descendants by repeating unequal cell divisions with an average interdivision time half that of the normal phenotype, whereas the normal daughter retained normal phenotypic characteristics. The results suggest one possible non-genetic inheritance of cellular characteristics where phenotypic differences can only be inherited by geometrical information, independent of specific gene regulation.
DOI
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