Very high-speed nanoimaging

Researchers at the Georgia Institute of Technology have built a new device which is 100 times faster than current nano imaging technology. Not only this device is much faster, it is also able to take movies and to simultaneously capture several physical properties of nanostructures, such as stiffness, elasticity or viscosity.

Researchers at the Georgia Institute of Technology have built a new device which is 100 times faster than current nano imaging technology. Not only the FIRAT (Force sensing Integrated Readout and Active Tip) is much faster than atomic force microscopy (AFM), it also is able to take movies and to simultaneously capture several physical properties of nanostructures, such as stiffness, elasticity or viscosity. In fact, the FIRAT probe, which works like a microphone, could one day replace AFM. As said one of the researchers, "We've multiplied each of the old capabilities by at least 10, and it has lots of new applications."

Here is the introduction of this Georgia Tech news release about this project led by Dr. Levent Degertekin.

Georgia Tech researchers have created a highly sensitive atomic force microscopy (AFM) technology capable of high-speed imaging 100 times faster than current AFM. This technology could prove invaluable for many types of nano-research, in particular for measuring microelectronic devices and observing fast biological interactions on the molecular scale, even translating into movies of molecular interactions in real time.

So how does this new microphone-inspired probe work?

FIRAT works a bit like a cross between a pogo stick and a microphone. In one version of the probe, the membrane with a sharp tip moves toward the sample and just before it touches, it is pulled by attractive forces. Much like a microphone diaphragm picks up sound vibrations, the FIRAT membrane starts taking sensory readings well before it touches the sample.

Below here is an image of the FIRAT probe which works like a microphone with is membrane (Credit: Georgia Tech).

The FIRAT probe

And when the tip hits the surface, the elasticity and stiffness of the surface determines how hard the material pushes back against the tip. So rather than just capturing a topography scan of the sample, FIRAT can pick up a wide variety of other material properties.

And here is an image showing the various measurements that can be captured simultaneously by the FIRAT device "including (from upper left to right) topography, adhesion energy, contact time and stiffness" (Credit: Georgia Tech).

FIRAT simultaneous measurements

This research work has been published by the Review of Scientific Instruments under the title "A new atomic force microscope probe with force sensing integrated readout and active tip" (Volume 77, Issue 2, Article 023501, February 2006). Here is a link to the abstract.

We introduce a novel probe structure for the atomic force microscope. The probe has a sharp tip placed on a micromachined membrane with an integrated displacement sensor, a diffraction-based optical interferometer. [...] We also produce tapping mode images of sample topography an order of magnitude faster than current probe microscopes using an integrated electrostatic actuator to move the probe tip. We envision a broad range of applications for this device that range from life sciences to microelectronics.

But what kind of applications will be made possible with this new device? They could include material property imaging and parallel molecular assays for drug screening and discovery. But as said Degertekin, "AFM started as a topography tool and has exploded to many more uses since. I'm sure people will find all sorts of uses for FIRAT that I haven’t imagined."

Sources: Georgia Institute of Technology news release, February 9, 2006; and various web sites

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