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Video AFM™ - FAQs

General Questions

1) What are the features of the VideoAFM™?

• Video rate operation, 1000 times faster than conventional AFM.
  • 25 frames per second at 128 x 128 pixels
  • 15 frames per second at 256 x 256 pixels
• Air and liquid operation
• Resolution comparable to conventional AFM (contact mode)
• Operates in conjunctionwith 3rd party conventional AFM
• Very simple non-invasive installation
• Can image in high vibration environment

2) What are the main components in a VideoAFM™ system?

• Workstation
• High-speed scan head
• Microscanners
• Cantilevers (specific to the VideoAFM™)

See specification sheet for more details

3) How fast is the VideoAFM™?

• 25 frames per second at 128 x 128 pixels
• 15 frames per second at 256 x 256 pixels

4) What is the maximum XY scan area?

• Air operation: 3µm x 3µm
• Liquid operation: 1µm x 1µm

5) What is the maximum Z scan range?

Typically, corrugations up to 100nm in air and 25nm in liquid, dependent on spatial frequency.

6) What is the XY resolution?

The resolution is comparable to conventional contact mode AFM imaging - approximately 10 nm (tip, sample and host AFM dependant).

7) What is the Z resolution?

The Z resolution <1nm, tip, sample and host AFM dependent.

8) Which microscopes are compatible with the VideoAFM™?

The VideoAFM™ is compatible with the vast majority of commercially available atomic force microscopes.

Please contact your sales representative for further information.

9) How long does it take to swap between conventional AFM and VideoAFM™ imaging?

The interface with the conventional AFM is quick and simple and it takes no more than a few minutes to attach the VideoAFM™. It monitors a small number of signals from the base microscope, which are routed directly into the back of the controller. There must also be enough room for the scan stage beneath the cantilever; 30 x 30 x 20 mm clearance is required (WxDxH).

The conventional AFM can be used as normal either with the VideoAFM™ switched off, or in conjunction with the VideoAFM™ when it is turned on.

10) Do you supply standard AFMs?

Infinitesima does not supply the conventional AFM, the VideoAFM™ is an attachment designed to fit on a wide range of microscopes to enhance the user's capabilities.

11) Is the VideoAFM™ an attachment to conventional AFM systems?

Yes.

12) Is the VideoAFM™ compatible with my existing AFM?

The VideoAFM™ is compatible with most AFMs.

Please contact your sales representative for further information.

13) Are the microscanners reuseable?

Infinitesima recommends using a new scanner with each new sample.

14) What do the consumables cost?

Please contact your sales representative for further information.

15) Does Infinitesima recommend a particular AFM system?

Infinitesima do not recommend a particular microscope. The VideoAFM™ is designed to work with a wide range of systems, each with their own capabilities.

16) How much data is collected?

Working at 256 x 256 pixels (full data, no compression), the VideoAFM™ produces movies with size of about 1 MB per second of recording. These can be burnt onto DVD, put onto memory sticks or alternatively archived on the controller.

17) How much does it cost?

Please contact your sales representative for further information.

Modes of Operation

1) Does the VideoAFM™ operate in contact mode?

When using the VideoAFM™, the conventional AFM is used in contact mode.

However, preconceptions about contact mode do not apply to the VideoAFM™. At these much higher scan speeds, the tip/sample interaction time is greatly reduced for specific points on the sample, dramatically changing the nature of the interaction, so much softer samples are able to be imaged than on a conventional AFM in contact mode.

Correspondingly, hard surfaces do not wear the tip down as in traditional slowscanning contact mode.

2) Can I use the VideoAFM™ cantilever in tapping mode?

Yes, in liquid operation.

Please contact your sales representative for further information.

3) Is it calibrated? Can we use it for CD (critical dimension) metrology?

The VideoAFM™ is calibrated in the slow scan axis and can be self calibrated in the facts scan by comparing features from traditionally AFM images or by moving a specified distance using the conventional AFM. Ask our sales representative for a demonstration.

4) How does the feedback work?

One of the factors limiting the maximum speed of operation of a conventional AFM is the electronic feedback system. The VideoAFM™ overcomes this limitation by removing the requirement for an electronic feedback system by utilising the intrinsic mechanical properties of a specially designed and engineered cantilever to enable the tip to track the surface of the sample at very high speed (greater than 10 cm per second).

A constant force image is generated by applying a Direct Force™ to the tip of the cantilever. The imaging force is controlled by adjusting the magnitude of the Direct Force™. This is a key technology in enabling the video rate imaging and has taken many years to perfect.

5) Does it use conventional cantilevers?

The VideoAFM™ uses specialist silicon nitride cantilevers that can be purchased in packs of 10, 50 or 100.

6) Does it work in liquid? What are the differences?

Yes, the VideoAFM™ does work in liquid. Operation in liquid requires upgrade package, which includes a liquid scan head, additional liquid module for controller and a starter pack of consumables including liquid microscanners and liquid VideoAFM™ levers.

7) Can you work at elevated temperatures? Do you supply a heating stage? What temperatures can you work at?

The VideoAFM™ is designed to operate at ambient temperatures. However, we have researches using the VideoAFM™ to observe polymer process presently at temperatures up to ~ 80 deg C and have successfully imaged the surface of a molten polymer crystallising.

Please contact Infinitesima for advice for operating the VideoAFM™ at elevated temperatures.

8) The scan area is quite small. Is that a problem?

Maximum images size is about 3 microns square in air, but as the VideoAFM™ is giving you a video rate image, you can simply move around much larger areas. Also these images can be stitched together to create highly detailed images of larger areas, all in a fraction of the time of conventional imaging.

9) What file formats and length of video can be collected?

The movies are saved in AVI file format, a standard that gives the VideoAFM™ the most flexibility. The data can be reviewed as a movie or with any video editing software. The movies remain uncompressed, so no data is lost due to encoding. Video durations are only limited by the MS Windows file size limitations. You would have to record a video for over an hour for this to be a problem. That's over 50,000 images at 256 x 256 pixels!

Samples & Sample Preparation

1) What surfaces can be imaged?

As with any AFM, the VideoAFM™ can image a wide variety of samples and with the real-time direct force interaction, you can control your interaction with much more delicate samples than might be assumed.

Commonly used samples are:

• Polymer films
• Biological samples, e.g. collagen, DNA
• Silicon structures

2) Can the VideoAFM™ measure soft samples like living cells or molecules?

Yes.

3) Can you use any standard cantilever with the VideoAFM™?

The VideoAFM™ uses special cantilevers.

4) Can the VideoAFM™ image DNA, proteins or antigens?

The VideoAFM™ is available with liquid operation. However, the usual sample considerations must be taken into account as for ANY AFM technique. The instrument has been used to image DNA in air, so it is possible to image biological polymers. Infinitesima are currently working with a number of groups to develop sample preparation and VideoAFM™ techniques for imaging biological molecules in liquid.

5) Does fast scanning in contact mode damage soft samples?

The high tip velocity of the VideoAFM™ means that the tip/sample interaction is different to conventional AFM. For example, Infinitesima have successfully imaged the surface of a molten polymer. As for ANY AFM technique, high contact forces and imaging for long periods of time can degrade samples.

6) What are the sample size limitations?

The sample size is limited by its mass which affects the resonant frequency microscanner and in turn the speed of the VideoAFM™. Infinitesima provides convenient sample mounting blocks with dimensions 0.8 x 0.8 x 0.6 mm.

Please contact your sales representative for further information.