Engineers from the Massachusetts Institute of Technology (MIT) have developed a new atomic force microscope (AFM) that is capable of scanning atom-sized structures around 2,000 times faster compared to conventional models.
The developers have since used the breakthrough technology to create images of various chemical processes that occur on a nanoscale. The speed of the AFM has allowed them to document these occurrences at a rate that approaches real-time video recording.
In a study featured in the journal Ultramicroscopy, Prof. Kamal Youcef-Toumi and his colleagues at MIT carried out tests on the capabilities of an AFM design made by Iman Soltani Bozchalooi.
The engineers first scanned a calcite sample measuring at around 70-by-70-microns as it is exposed to deionized water and later on to sulfuric acid. They witnessed how the acid ate away at the calcite sample and expand the nanometer-sized pits that already existed in the material.
The pits quickly began to merge and caused the layers of calcite to be removed along the crystal pattern of the material over the course of a few seconds.
Youcef-Toumi explained that the speed and sensitivity of the new atomic force microscope design provides scientists with an opportunity to observe atomic-sized events as they occur as high-resolution "movies."
He said that researchers can now witness events, such as the deposition, dissolution, condensation and nucleation of material on a scale that they have never observed before.
Youcef-Toumi pointed out that seeing such details emerge allows them to explore the world on a nanoscale
Existing AFMs typically scan sample materials through the use of an ultrafine probe that skims along the surface of the material to trace its topography much like how blind people read Braille. The sample is placed on a movable platform that moves it vertically and laterally under the ultrafine probe.
Since AFMs are designed to scan atom-sized structures, the process often takes a long time to finish as instruments progress slowly to prevent sudden shifts that could alter the scanning of the sample. Conventional AFMs typically take around a second to scan one to two lines.
Bozchalooi's design utilizes a multiactuated scanner, which makes use of a combination of a larger, slower scanner and a smaller speedier scanner that can go in different directions. These scanners allow the system to scan a wide three-dimensional region at very high speeds.
Bozchalooi created control algorithms specifically designed to consider the effect on the various scanners on each other in order to simplify the processing of the multiactuated instrument.
The MIT researchers discovered that the Bozchalooi's AFM design is capable of scanning a calcite sample forward and backward without causing any damage to the sample or the scanner's probe.
The new AFM can also scan a sample material at rates beyond 2,000 hertz, or around 4,000 lines per second, which is 2,000 times faster compared to commercial AFMs that are already available. This means the instrument can process around eight to 10 frames per second.
According to Bozchalooi, the AFM currently has no limit on its maximum probe speed and imaging range and can scan hundreds of microns across and image features that are a few microns high.
Youcef-Toumi said that their goal is to reach the rate of real-time video, which is around 30 frames per second, in their AFM scanning.
