Atomic Force Microscope Can Capture Chemical Reactions Like a Movie

A chemical reaction captured using MIT’s AFM. (Image courtesy of MIT/Youtube).

Microscopes have long provided the ability to observe the stages of processes like condensation and nucleation as they happen. The issue is that they can’t always help when it’s necessary to revisit observations under exactly the same circumstances.

Or can they?

An atomic force microscope (AFM) capable of scanning images 2,000 times faster than existing commercial models has recently been developed by MIT engineers. Images of structures as small as a fraction of a nanometer can be captured by AFMs.

The speed of MIT’s AFM will allow researchers to watch videos of atomic-sized processes.

However, as the images will be about eight to 10 frames per second, the video will be less smooth than a traditional movie. Nonetheless, engineers will be able to watch processes like condensation, nucleation or dissolution in a bid to optimize these processes in industry.

AFMs usually scan a sample’s topology by tracing an ultrafine probe or needle across the surface. The scanner acts as a moveable platform that will adjust the probe across the sample laterally and vertically. The AFM is capable of scanning extremely small structures but to avoid altering the sample or distorting the image, the instruments have to work slowly and go line by line.

Close-up of microscope shows tubes that inject various liquids into the imaging environment. (Image courtesy of Jose-Luis Olivares/MIT)

The scanning process can be sped up by adding more probes. However, the movements of each probe can affect the results of the others. Past attempts at multi-actuated scanners have been hindered mostly because of how these two probes interfere with each other.

However, MIT’s AFM includes a control algorithm which takes the movements of multiple probes into consideration when capturing the image. This allows for the design to incorporate multi-actuated scanners to probe the sample simultaneously. As a result, MIT’s platform combines a smaller, faster scanner and a larger, slower scanner to capture every angle.

Conventional AFMs scan roughly one to two lines per second. However, MIT says its improvements allow its AFM to work 2,000 times faster.

For example, traditional AFM scanners might take 10 minutes to capture an image of a static sample. However, if the sample is undergoing changes traditional AFMs will provide incorrect information. By the time the probes reach the bottom, the sample could look entirely different. MIT’s high-speed scanner, however, allows researchers to watch the sample change more accurately.

The design enables high-speed scanning over large and small ranges. (Image courtesy of: Jose-Luis Olivares/MIT).

The design is based off of the work of Iman Soltani Bozchalooi, who is a postdoctoral candidate in MIT’s department of engineering. The research was supported by the Center for Clean Water and Clean Energy at MIT,KFUPM and National Instruments. For more information, visit MIT’s website.