Magnetic resonance force microscopy

Magnetic resonance force microscopy

Magnetic resonance force microscopy (MRFM) is an imaging technique that acquires magnetic resonance images (MRI) at nanometer scales, and possibly at atomic scales in the future. MRFM is potentially able to observe protein structures which cannot be seen using X-ray crystallography and protein nuclear magnetic resonance spectroscopy. Detection of the magnetic spin of a single electron has been demonstrated using this technique. The sensitivity of a current MRFM microscope is 10 billion times better than a medical MRI used in hospitals.

Contents

Basic principle

The MRFM concept combines the ideas of magnetic resonance imaging (MRI) and atomic force microscopy (AFM). Conventional MRI employs an inductive coil as an antenna to sense resonant nuclear or electronic spins in a magnetic field gradient. MRFM uses a cantilever tipped with a ferromagnetic (iron cobalt) particle to directly detect a modulated spin gradient force between sample spins and the tip. As the ferromagnetic tip moves close to the sample, the atoms’ nuclear spins become attracted to it and generate a small force on the cantilever. The spins are then repeatedly flipped, causing the cantilever to gently sway back and forth in a synchronous motion. That displacement is measured with an interferometer (laser beam) to create a series of 2-D images of the sample, which are combined to generate a 3-D image. The interferometer measures resonant frequency of the cantilever. Smaller ferromagnetic particles and softer cantilevers increase the signal to noise ratio. Unlike the inductive coil approach, MRFM sensitivity scales favorably as device and sample dimensions are reduced.

Because the signal to noise ratio is inversely proportional to the sample size, Brownian motion is the primary source of noise at the scale in which MRFM is useful. Accordingly, MRFM devices are cryogenically cooled. MRFM was specifically devised to determine the structure of proteins in situ.

Milestones

The basic principles of MRFM imaging and the theoretical possibility of this technology were first described in 1991[1]. The first MRFM image was obtained in 1993 at the IBM Almaden Research Center with 1-μm vertical resolution and 5-μm lateral resolution using a bulk sample of the paramagnetic substance diphenyipicrylhydrazil[2]. The spatial resolution reached nanometer-scale in 2003.[3] Detection of the magnetic spin of a single electron was achieved in 2004[4]. In 2009 researchers at IBM and Stanford announced that they had achieved resolution of better than 10 nanometers, imaging tobacco mosaic virus particles on a nanometer-thick layer of adsorbed hydrocarbons.[5]

External links

References

  1. ^ J. A. Sidles (1991). "Noninductive detection of single-proton magnetic resonance". Applied Physics Letters 58: 2854–6. Bibcode 1991ApPhL..58.2854S. doi:10.1063/1.104757. 
  2. ^ O. Zuger and D. Rugar (1993). "First images from a magnetic resonance force microscope". Applied Physics Letters 63: 2496–8. Bibcode 1993ApPhL..63.2496Z. doi:10.1063/1.110460. 
  3. ^ S. Chao, W. Dougherty, J. Garbini, J. Sidles (2003). "Nanometer-scale magnetic resonance imaging". Review of Scientific Instruments 75: 1175–81. Bibcode 2004RScI...75.1175C. doi:10.1063/1.1666983. 
  4. ^ D. Rugar, R. Budakian, H. Mamin, B. Chui (2004). "Single spin detection by magnetic resonance force microscopy". Nature 430 (6997): 329–32. Bibcode 2004Natur.430..329R. doi:10.1038/nature02658. PMID 15254532. 
  5. ^ C. L. Degen, M. Poggio, H. J. Mamin, C. T. Rettner, and D. Rugar (2009). "Nanoscale magnetic resonance imaging". PNAS 106 (5): 1313. Bibcode 2009PNAS..106.1313D. doi:10.1073/pnas.0812068106. PMC 2628306. PMID 19139397. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2628306. 

Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Magnetic resonance microscopy — (MRM, µMRI) is Magnetic Resonance Imaging (MRI) at a microscopic level. A strict definition is MRI having voxel resolutions of better than 100 µm³ [1]. Contents 1 Nomenclature 2 Differences between MRI and MRM …   Wikipedia

  • Magnetic resonance imaging — MRI redirects here. For other meanings of MRI or Mri, see MRI (disambiguation). Magnetic resonance imaging Intervention Sagittal MR image of the knee ICD 10 PCS B?3?ZZZ …   Wikipedia

  • Magnetic force microscope — MFM images of 3.2 GB and 30 GB computer hard drive surfaces. Magnetic force microscope (MFM) is a variety of atomic force microscope, where a sharp magnetized tip scans a magnetic sample; the tip sample magnetic interactions are detected and used …   Wikipedia

  • Scanning probe microscopy — Part of a series of articles on Nanotechnology …   Wikipedia

  • Microscopie à force de résonance magnétique — La microscopie à force de résonance magnétique (en anglais, magnetic resonance force microscopy) est un procédé de nano IRM développé depuis le début des années 1990. Sommaire 1 Principe 2 Histoire 3 Référence 4 …   Wikipédia en Français

  • Résonance magnétique nucléaire — Pour les articles homonymes, voir RMN. Premier spectromètre RMN à 1 GHz (23,5 T installé au Centre de RMN à Très Hauts Champs à Lyon en aôut 2009. La résonance magnétique nucléaire (RMN) désigne une propriété de certains noyaux atomiques …   Wikipédia en Français

  • Scanning voltage microscopy — (SVM) sometimes also called nanopotentiometry is a scientific experimental technique based on atomic force microscopy. A conductive probe, usually only a few nanometers wide at the tip, is placed in full contact with an operational electronic or… …   Wikipedia

  • Atomic force microscope — The atomic force microscope (AFM) or scanning force microscope (SFM) is a very high resolution type of scanning probe microscope, with demonstrated resolution of fractions of a nanometer, more than 1000 times better than the optical diffraction… …   Wikipedia

  • Kelvin probe force microscope — Kelvin probe force microscopy ( KPFM ), also known as surface potential microscopy, is a noncontact variant of atomic force microscopy (AFM) that was [http://dns.ntu ccms.ntu.edu.tw/references/APPL PHYS LETT 58 2921 1991.pdf invented] in 1991.… …   Wikipedia

  • National High Magnetic Field Laboratory — logo the National High Magnetic Field Laboratory (NHMFL) is a laboratory at Florida State University, with branches in University of Florida and at Los Alamos National Laboratory. NHMFL develops and research at magnetic fields for research in… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”