RSI Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Sep 2003

Volume 74, Issue 9, pp. 3909-4222

Return to All Sections
back to top
RSS Feeds
back to top MICROSCOPY and IMAGING

Oscillatory magnetic tweezers based on ferromagnetic beads and simple coaxial coils

Xavier Trepat, Mireia Grabulosa, Lara Buscemi, Fèlix Rico, Ben Fabry, Jeffrey J. Fredberg, and Ramon Farré

Rev. Sci. Instrum. 74, 4012 (2003); http://dx.doi.org/10.1063/1.1599062 (9 pages) | Cited 8 times

Online Publication Date: 20 August 2003

Full Text: | Download PDF

Show Abstract
We report the design and validation of simple magnetic tweezers for oscillating ferromagnetic beads in the piconewton and nanometer scales. The system is based on a single pair of coaxial coils operating in two sequential modes: permanent magnetization of the beads through a large and brief pulse of magnetic field and generation of magnetic gradients to produce uniaxial oscillatory forces. By using this two step method, the magnetic moment of the beads remains constant during measurements. Therefore, the applied force can be computed and varies linearly with the driving signal. No feedback control is required to produce well defined force oscillations over a wide bandwidth. The design of the coils was optimized to obtain high magnetic fields (280 mT) and gradients (2 T/m) with high homogeneity (5% variation) within the sample. The magnetic tweezers were implemented in an inverted optical microscope with a videomicroscopy-based multiparticle tracking system. The apparatus was validated with 4.5 μm magnetite beads obtaining forces up to ∼2 pN and subnanometer resolution. The applicability of the device includes microrheology of biopolymer and cell cytoplasm, molecular mechanics, and mechanotransduction in living cells. © 2003 American Institute of Physics.
Show PACS
85.70.-w Magnetic devices
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
87.80.Fe Micromanipulation of biological structures
06.60.Sx Positioning and alignment; manipulating, remote handling

In situ manipulation and characterizations using nanomanipulators inside a field emission-scanning electron microscope

Keun Soo Kim, Seong Chu Lim, Im Bok Lee, Key Heyok An, Dong Jae Bae, Shinje Choi, Jae-Eun Yoo, and Young Hee Lee

Rev. Sci. Instrum. 74, 4021 (2003); http://dx.doi.org/10.1063/1.1597955 (5 pages) | Cited 13 times

Online Publication Date: 20 August 2003

Full Text: | Download PDF

Show Abstract
We have used two piezoelectric nanomanipulators to manage the multiwalled carbon nanotubes (MWCNTs) within the field emission-scanning electron microscope (FE-SEM). For an easy access of a tungsten tip to MWCNTs, we prepared the tungsten tip in sharp and long tip geometry using different electrochemical etching parameters. In addition, the sample stage was tilted by 45° from the normal direction of the surface to allow a better incident angle to the approaching tungsten tip. For manipulations, a nanotube or the bundles were attached at the tungsten tip using an electron beam-induced deposition (EBID). Using two manipulators, we have then fabricated a CNT-based transistor, a cross-junction of MWCNTs, and a CNT-attached atomic force microscopy tip. After these fabrications, the field emission properties of the MWCNT and junction properties of the MWCNT and the tungsten tip have been investigated. We found that the EBID approach was very useful to weld the nanostructured materials on the tungsten tip by simply irradiating the electron beam, although this sometimes increased the contact resistance by depositing hydrocarbon materials. © 2003 American Institute of Physics.
Show PACS
06.60.Sx Positioning and alignment; manipulating, remote handling
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
85.35.Kt Nanotube devices
07.79.Lh Atomic force microscopes
07.07.Tw Servo and control equipment; robots
81.07.De Nanotubes
82.45.Jn Surface structure, reactivity and catalysis
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.65.Cf Surface cleaning, etching, patterning
85.30.Pq Bipolar transistors
85.30.Tv Field effect devices
81.16.Ta Atom manipulation
68.37.Ps Atomic force microscopy (AFM)
73.40.Cg Contact resistance, contact potential

Calibration of colloid probe cantilevers using the dynamic viscous response of a confined liquid

Shannon M. Notley, Simon Biggs, and Vincent S. J. Craig

Rev. Sci. Instrum. 74, 4026 (2003); http://dx.doi.org/10.1063/1.1597950 (7 pages) | Cited 10 times

Online Publication Date: 20 August 2003

Full Text: | Download PDF

Show Abstract
A method is described to determine the spring constant of colloid probe cantilevers used in force measurements with the atomic force microscope. An oscillatory drive applied to the substrate is coupled by viscous interactions to the colloid probe. The dynamic response of the probe, which is unaffected by static interactions, is then used to determine the spring constant of the cantilever. Thus an accurate calibration of the spring constant may be performed simultaneously with a normal colloidal probe force measurement in situ. © 2003 American Institute of Physics.
Show PACS
07.79.Lh Atomic force microscopes
07.10.Pz Instruments for strain, force, and torque
83.80.Hj Suspensions, dispersions, pastes, slurries, colloids
66.20.-d Viscosity of liquids; diffusive momentum transport
82.70.Dd Colloids
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close