Atomic force microscopy, or AFM, is a widely used technique that can quantitatively map material surfaces in three dimensions, but its accuracy is limited by the size of the microscope’s probe. A new AI technique overcomes this limitation and allows microscopes to resolve material features smaller than the probe’s tip.
“Accurate surface height profiles are crucial to nanoelectronics development as well as scientific studies of material and biological systems, and AFM is a key technique that can measure profiles noninvasively,” said Yingjie Zhang, a U. of I. materials science & engineering professor and the project lead. “We’ve demonstrated how to be even more precise and see things that are even smaller, and we’ve shown how AI can be leveraged to overcome a seemingly insurmountable limitation.”
Often, microscopy techniques can only provide two-dimensional images, essentially providing researchers with aerial photographs of material surfaces. AFM provides full topographical maps accurately showing the height profiles of the surface features. These three-dimensional images are obtained by moving a probe across the material’s surface and measuring its vertical deflection.
If surface features approach the size of the probe’s tip—about 10 nanometers—then they cannot be resolved by the microscope because the probe becomes too large to “feel out” the features. Microscopists have been aware of this limitation for decades, but the U. of I. researchers are the first to give a deterministic solution.
“We turned to AI and deep learning because we wanted to get the height profile—the exact roughness—without the inherent limitations of more conventional mathematical methods,” said Lalith Bonagiri, a graduate student in Zhang’s group and the study’s lead author.
The researchers developed a deep learning algorithm with an encoder-decoder framework. It first “encodes” raw AFM images by decomposing them into abstract features. After the feature representation is manipulated to remove the undesired effects, it is then “decoded” back into a recognizable image.
To train the algorithm, the researchers generated artificial images of three-dimensional structures and simulated their AFM readouts. The algorithm was then constructed to transform the simulated AFM images with probe-size effects and extract the underlying features.
“We actually had to do something nonstandard to achieve this,” Bonagiri said. “The first step of typical AI image processing is to rescale the brightness and contrast of the images against some standard to simplify comparisons. In our case, though, the absolute brightness and contrast is the part that’s meaningful, so we had to forgo that first step. That made the problem much more challenging.”
To test their algorithm, the researchers synthesized gold and palladium nanoparticles with known dimensions on a silicon host. The algorithm successfully removed the probe tip effects and correctly identified the three-dimensional features of the nanoparticles.
“We’ve given a proof-of-concept and shown how to use AI to significantly improve AFM images, but this work is only the beginning,” Zhang said. “As with all AI algorithms, we can improve it by training it on more and better data, but the path forward is clear.”
More information: Lalith Krishna Samanth Bonagiri et al, Precise Surface Profiling at the Nanoscale Enabled by Deep Learning, Nano Letters (2024). DOI: 10.1021/acs.nanolett.3c04712

News
Natural Plant Extract Removes up to 90% of Microplastics From Water
Researchers found that natural polymers derived from okra and fenugreek are highly effective at removing microplastics from water. The same sticky substances that make okra slimy and give fenugreek its gel-like texture could help [...]
Instant coffee may damage your eyes, genetic study finds
A new genetic study shows that just one extra cup of instant coffee a day could significantly increase your risk of developing dry AMD, shedding fresh light on how our daily beverage choices may [...]
Nanoneedle patch offers painless alternative to traditional cancer biopsies
A patch containing tens of millions of microscopic nanoneedles could soon replace traditional biopsies, scientists have found. The patch offers a painless and less invasive alternative for millions of patients worldwide who undergo biopsies [...]
Small antibodies provide broad protection against SARS coronaviruses
Scientists have discovered a unique class of small antibodies that are strongly protective against a wide range of SARS coronaviruses, including SARS-CoV-1 and numerous early and recent SARS-CoV-2 variants. The unique antibodies target an [...]
Controlling This One Molecule Could Halt Alzheimer’s in Its Tracks
New research identifies the immune molecule STING as a driver of brain damage in Alzheimer’s. A new approach to Alzheimer’s disease has led to an exciting discovery that could help stop the devastating cognitive decline [...]
Cyborg tadpoles are helping us learn how brain development starts
How does our brain, which is capable of generating complex thoughts, actions and even self-reflection, grow out of essentially nothing? An experiment in tadpoles, in which an electronic implant was incorporated into a precursor [...]
Prime Editing: The Next Frontier in Genetic Medicine
By Dr. Chinta SidharthanReviewed by Benedette Cuffari, M.Sc. Discover how prime editing is redefining the future of medicine by offering highly precise, safe, and versatile DNA corrections, bringing hope for more effective treatments for genetic diseases [...]
Can scientists predict life longevity from a drop of blood?
Discover how a new epigenetic clock measures how fast you are really aging from just a drop of blood or saliva. A recent study published in the journal Nature Aging constructed an intrinsic capacity (IC) clock [...]
What is different about the NB.1.8.1 Covid variant?
For many of us, Covid-19 feels like a chapter we’ve closed – along with the days of PCR tests, mask mandates and daily case updates. But while life may feel back to normal, the [...]
Scientists discover single cell creatures can learn new behaviours
It was previously thought that learning behaviours only applied to animals with complex brain and nervous systems, but a new study has proven that this may also occur in individual cells. As a result, this new evidence may change how [...]
Virus which ’causes multiple organ failure’ found at popular Spanish holiday destination
British tourists planning trips to Spain have been warned after a deadly virus that can cause multiple organ failure has been detected in the country. The Foreign Office issued the alert on its dedicated website Travel [...]
Urgent health warning as dangerous new Covid virus from China triggers US outbreak
A dangerous new Covid variant from China is surging in California, health officials warn. The California Department of Public Health warned this week the highly contagious NB.1.8.1 strain has been detected in the state, making it the [...]
How the evolution of a single gene allowed the plague to adapt, prolonging the pandemics
Scientists have documented the way a single gene in the bacterium that causes bubonic plague, Yersinia pestis, allowed it to survive hundreds of years by adjusting its virulence and the length of time it [...]
Inhalable Nanovaccines: The Future of Needle-Free Immunization
The COVID-19 pandemic highlighted the need for adaptable and scalable vaccine technologies. While mRNA vaccines have improved disease prevention, most are delivered by intramuscular injection, which may not effectively prevent infections that begin at [...]
‘Stealthy’ lipid nanoparticles give mRNA vaccines a makeover
A new material developed at Cornell University could significantly improve the delivery and effectiveness of mRNA vaccines by replacing a commonly used ingredient that may trigger unwanted immune responses in some people. Thanks to [...]
You could be inhaling nearly 70,000 plastic particles annually, what it means for your health
Invisible plastics in the air are infiltrating our bodies and cities. Scientists reveal the urgent health dangers and outline bold solutions for a cleaner, safer future. In a recent review article published in the [...]