Magnetic Force Microscopy

Magnetic force microscopy (MFM), is a family of techniques used to measure magnetic fields using an AFM. In fact there are a large number of different  techniques used to measure magnetic properties, but in general, they all use the AFM to measure the oscillation of a magnetically sensitive probe when it is far (5-100 nm) from the sample surface. MFM probes are usually made by coating normal silicon probes with a thin magnetic coating. The magnetic coating means that the oscillation of the probe will change when in a magnetic field. However, when the probe is touching the sample, the short range tip-sample forces will obscure the magnetic forces (which are much weaker). Fortunately, since magnetic forces can be measured at a distance, it is possible to remove the probe from the surface, and still measure magnetic forces, while removing these short range forces. In order to make accurate measurements, the probe should be at the same distance from the sample throughout the image. There are a number of techniques to do this, which are reviewed in [1], but in most commercial implementations, the so-called “Lifting” method first used by Bard [2] is used. This method is illustrated schematically below.

 

How MFM lifting modes work

In order to make MFM measurements with this lifting mode, an oscillating mode is used, typically intermittent contact mode AFM. For each line of the image, two scans are made. In the first line, the topography is measured as usual. The probe is then lifted a user-defined distance above the surface (typically in the range 5 to 50 nm). The second line will then be measured, but the topography measured in the first line is added to the height of the probe as it scans along the line. In this way, the instrument attempts to keep the probe at exactly the same distance from the sample surface at each point in the MFM image. MFM is widely used to generate images of magnetic fields associated with small domains, and is particularly of use in the development of magnetic recording technology . It can also show magnetic fields associated with individual magnetic nanoparticles[3]. However, interpretation of MFM signals is complicated by the unknown nature of the probe, and it is limited to measuring fairly intense fields[4,1].

mfm

The image above shows topogrpahic (left) and magnetic field (right) images of a cluster of magnetic nanoparticles.

 

References

Eaton P et al. (2010) Atomic force microscopy. OUP, Oxford

Lin CW et al. (1987). J Electrochem Soc 134:1038-1039.

 Neves CS et al. (2010). Nanotechnology 21:305706.

Schreiber S et al. (2008). Small 4:270-278.


book coverThis article was condensed from “Atomic Force Microscopy” by Eaton and West, OUP, 2010. The article comes from Chapter 3, which describes all of the commonly used modes in Atomic Force Microscopes. The Article in the book also contains a full reference list.

 


Images in this article come from the book, and are Copyright Peter Eaton/ OUP 2010.

At the moment, I have disabled user registration and login. Most of you never login, and the only advantage to do so, is that you can submit pictures to the gallery, so it wont have much negative effect. I did this because the user registraiton was getting spammed with fake accounts. If I figure out how to add some effective captcha to stop this heppening, I may re-enable the user menu in the future.

-Pete

This instrument is supervised by: Peter Eaton, contact: This email address is being protected from spambots. You need JavaScript enabled to view it.

Long Beach AFM Computer WorkstationLong Beach AFM Head

Instrument Information

This instrument is a modified TT-AFM from AFM Workshop.

It is equipped with two scanners, enabling large (low resolution ) or small (high resolution) scanners. It has an experimental liquid cell for in-situ measurements.

Here are more detailed specifications:

  • Instrument Configuration: Light lever (optical lever) - based sample-scanning AFM
  • Sample Sizes:ca. 13x13x5 mm
  • Imaging Modes: vibrating (tapping), non-vibrating (contact), phase imaging, lateral force microscopy (friction force microscopy)*
  • Imaging Environment: Air or Liquid* (experimental).
  • Z-translation: Vertical direct drive (1micron resolution)
  • XY Translation: manual micrometers
  • Video Optical Microscope: Zoom to 400X, 3 micron resolution (3M pixel camera)
  • Scan Range: 70x70x17 microns or 20x20x7 microns
  • Linearisation: All axes (x, y and z) with strain gauges, which can be turned off for enhanced signal to noise ratio.
  • Z noise level: less than 0.2 Angstrom
  • Vibration isolation: compact passive vibration isolation


*These features are not yet tested.

Booking Schedule and Calendar:

phase image of ecoli many bacteria amplitude e. coli
Phase image of E. coli Many E. coli Amplitude E. coli
Grid spore sin phase cells and spore

Silicon grid showing
linearity

Phase image of
spores
Cell growing from
spores - 3D 
leishmania cell epithelial cell
Leishmania cell Epithelial cell



Protocols

Back to Requimte Page

This instrument is supervised by: Peter Eaton; Please contact Peter for any enquiries regarding access to the lab, or training or use of the instruments. Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

TTAFM at porto

 

Instrument #1: Long Beach

This instrument is a modified TT-AFM from AFM Workshop.

It is equipped with two scanners, enabling large (low resolution) or small (high resolution) sample imaging. It has an standard liquid cell for in-situ measurements, and a custom-made liquid heater cell (ambient to 60 celcius), with 0.1 degree accuracy. It has been upgraded with two new ADC cards, so it's now capable of recording 12 channels simultaneously, and displaying a life feed of height, scanner voltage, amplitude, etc (see left image above). It's installed in a custom-made vibration and acoustic isolation cabinet.

Here are more detailed specifications:

  • Instrument Configuration: Optical lever - based sample-scanning AFM
  • Sample Size: Maxmium ca. 20x20x5 mm
  • Imaging Modes: vibrating (tapping), non-vibrating (contact), phase imaging, lateral force microscopy (friction force microscopy)*
  • Imaging Environment: Air or Liquid.
  • Imaging temperature ambient to 60 ºC
  • Z-translation: Vertical direct drive (1 micron resolution)
  • XY Translation: Manual
  • Video Optical Microscope: Zoom to 400X, 3 micron resolution (3M pixel camera)
  • Scan Range: 50x50x17 microns or 20x20x7 microns
  • Linearisation: All axes (x, y and z) with strain guages, can be turned off for enhanced signal to noise ratio
  • Z noise level: less than 0.2 Angstrom
  • Vibration isolation: Passive vibration isolation, with acoustic shielding

 

Instrument #2: San Diego

This is a Life Sciences AFM (model B) from AFM Workshop. It is a probe-scanning AFM with maximum 50 micron scan range. it is mounted on an inverted optical microscope, equipped for brightfield, phase, and fluorescence microscopy. We have both air and liquid scanning-capable probe holders. It is typically used for cell studies and other transparent samples. UPDATE: This instrument currently not available.



Booking Schedules and Calendars:

Click the link below to see the Longbeach Google calendar

TT-AFM - Longbeach

 

 

LS-AFM -San Diego - Calendar currently not available



Example Images
Here are just a few example images measured with the TT-AFM instrument on a variety of samples.

More images can be found in the LS-AFM image gallery and the TT-AFM image gallery.

many bacteria amplitude e. coli
Grid spores in phase cells and spore
leishmania cell epithelial cell  



TT-AFM Protocols



Troubleshooting

There is a Google Docs file I have created which contains the solutions to some problems that might crop up using the TT-AFM. This could also apply to other TT-AFM instruments. You can reach it (for viewing) via this link: TT-AFM troubleshooting. If you have something to add to the document, and wish to contribute, just email me (This email address is being protected from spambots. You need JavaScript enabled to view it.) for access.

Back to Requimte Page

 

phase image composite resinrequimte     The Manager of this instrument is:                 Francisco  Jorge Caldeira.
     Contact: This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it. 

          AFM Lab DQ-FCT-UNL, Caparica.

Hello
I am a TT-AFM from AFM workshop.com... I was born (Jorge Caldeira assembled me) in Signal Hill CA USA, so he named me...Signal Hill !
I travel from Signal Hill CA USA to Monte de Caparica Portugal ... Later I visit my twin machine Long Beach in Porto for the 2013 AFM  course, and to pay its visit to Caparica in the 2011 AFM course.
So both TT-AFM's were the first machines assembled and we traveled each almost 10 000 km ...so far...
See the place were I was made .... and Leonor's hair that I imaged and got her the AFM 2013 course prize...
 
Can I use AFM ?     Yes you can   ...

 signalhill Leonor hair details s

signalcaparica

GPS: LAT=38.66219, LONG -9.20867  Location: Room 119 DQ FCT UNL PT
 
 
 
Current Projects:
 

PEDOT on Paper 

Cesar Laia

Jorge Caldeira

 

 

 

Pf1 bacteriophage cytochrome c

electrostatic complex macroscopic fibers

 

Heber Silva

Ruben Chaves

Jorge Caldeira

Peter Eaton

CiiEM ISCSEM

Requimte

 

 

Tooth dentinal tubes

Acid atacked hipoclorite cleaned

 

João Oliveira

Jorge Caldeira

CiiEM ISCSEM Requimte FCT UNL

 


 

Polymeric nanoparticles, formed from polystyrene with pending hydrophilic glucose moieties

 

Krasimira Petrova

Requimte FCT UNL

 

 

Polymeric nanoparticles (PNPs) based on amphiphilic polymeric conjugates composed of cholic acid, sucrose and PEG. 

Carina Crucho

Teresa Barros

Requimte FCT UNL

 

 

Dental restoration resins and polishing systems

 

Rita Simões

Jorge Caldeira

CiiEM ISCSEM Requimte FCT UNL

 

 

 

Classic Maya chrysoprase maskette pendant ca. 800 AD 

 

Hugo Miguel Crespo

Faculdade de Letras Universidade de Lisboa

 

Ana Pereira

DCR FCT UNL

 

 

 

 

Core-shell polymeric nanoparticles, formed from polystyrene with pending bifunctional glucose

 Krasimira Petrova

Requimte FCT UNL

 

 

Nanoestructured (nanocal), synthesized from metallic Ca

CaO Þ Ca(OH)2 + CO2    Þ CaCO3

Giovanni Borsoi

LNEC Portugal

TU Delft Holland

 

Photochemical dendrimeric polymerization of tripodal coumarin

 João Avo

João Lima

Jorge Parola

Requimte FCT UNL





 

 

Pseudomonas aeruginosa with bacteriphage Pf1 | Patricia Montez  Héber Silva, Ruben Chaves Jorge Caldeira

Dechorosprillium sp Bacteria | Cristina Costa

Yeast | Madalena Oom

Magnetically Aligned Pf1 Virus + Protein assocaition | Ruben C., Héber S., Celina S., P. Eaton

Magnetic Nano Particles Fe3O4 "bare" 10x10 μm Image | Cecília Roque,  Sara Santana

 afm_scan_2011-01-24_03.22.11 10um 256 pixels right

 

 

 

 

 

 

 Vertically polsihed Tooth sample  20x20 μm Image  | J.Martins dos Santos, Ana Mano Azul,  Mario.Polido, João Oliveira e Jorge Caldeira

tooth

 

                               Instrument Information

signal hilll instrument with computer

 

 

 

 

 

 

 

 

 

This instrument is a modified TT-AFM from AFMWorkshop.

  • Instrument Configuration: Light lever (optical lever) - based sample-scanning AFM
  • Sample Sizes:ca. 13x13x5 mm
  • Imaging Modes: vibrating (tapping), non-vibrating (contact), phase imaging, lateral force microscopy (friction force microscopy)*
  • Imaging Environment: Air or Liquid* (experimental).
  • Z-translation: Vertical direct drive (1micron resolution)
  • XY Translation: manual micrometers
  • Video Optical Microscope: Zoom to 400X, 3 micron resolution (3M pixel camera)
  • Scan Range: 70x70x17 microns
  • Linearisation: All axes (x, y and z) with strain guages, can be turned off for enhanced signal to noise ratio.
  • Z noise level: less than 0.2 Angstrom
  • Vibration isolation: homemade passive solution

 

signal hill

Signal Hill Instrument closeup

Protocols

  • Startup Procedure
  • Shutdown Procedure
  • Scanning in contact "non-vibrating" mode
  • Scanning in tapping "vibrating" mode
  • These protocols are currently in development, meanwhile, here is a link to the latest version of the protocols word document for use of "Long Beach": TTAFM_protocols.doc

Back to Requimte Page           Go to Porto Lab Page




Subcategories