Northeastern University

CHN gets a new AFM

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My favorite days are the ones when I get to take field trips to labs. Last week, I was lucky enough to have two such experiences in one day. In one, I even got to play scientist again by decking out in head-to-toe clean-room garb.

My reason for visiting the Center for High Rate Nanomanufacturing today was to see their new atomic force microscope, which was donated to CHN by the company and will be available for the entire Northeastern community to use. First I got a lesson in AFM, as those in the know like to call it, and then I got to see the instrument in person.

Stylin' next to CHN's new atomic force microscope. Can you tell how excited I am?

Every atom exerts a miniscule force on its surroundings, either pushing or pulling against whatever is in its immediate vicinity. By immediate vicinity we’re talking angstrom scale — that’s somewhere between a billionth and trillionth of a meter. An AFM works by passing a tiny nanowire over the surface of a sample. Hanging from a miniature cantilever, the wire moves up and down in response to these atomic forces.

Here the iPhone failed me a little. It's blurry but it gives you a sense of the size. The cantilever is visible as a tiny line running vertically in the center of that little plate. The nanowire hangs off the cantilever, perpendicular to the plane of the image (your computer screen, I guess.)

A laser is focused on top of the cantilever and bends in response to the nanowire’s movements. A photo detector translates the angle of that light into data, resulting in a graphical image of the surface of the sample.

The kind of image the AFM produces.

CHN graduate student Hanchul Cho makes nanotemplates by layering elements like carbon nanotubes onto a substrate. He needs to know exactly how many elements have been deposited and how thick the templates are in order to calculate the electrical properties of the device. AFM is the method of choice for doing that.

The guts of the fancy new AFM.

Cho’s work is just one example of the many applications in which the microscope will be put to use at CHN said research scientist Siva Somu. It can also be used to figure out how tightly the nanoelements are bound to a surface and to determine the efficiency of transfer when they move the elements from a template onto a recipient substrate.

CHN already has one AFM, but it the new one, which is at the cutting edge of the technology, overcomes some challenges inherent to most AFMs. The new instrument is much better suited for extremely smooth surfaces without significant step changes, said Cho.

Guts of the old AFM.

Cho, by the way, is great. He hails from Korea and has the lucky opportunity to travel there for a ten day training session in using and maintaining the instrument. When he returns he’ll be the resident expert, so be sure to find him if you have any questions!

Cho and the AFM

 


One Comment

  1. Biggie_Robs wrote:

    Those are some big smiles–sounds like a cool machine!

    –R

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