Novel Methodology Has Potential to Transform Electron Microscopy

Scientists at Trinity College Dublin have developed a novel imaging technique that significantly reduces radiation exposure and imaging time in scanning transmission electron microscopes (STEMs). This approach, detailed in a recent Science paper, has the potential to enhance imaging capabilities across various fields, from materials science to medicine, particularly benefiting sensitive samples like biological tissues.

The new method challenges conventional STEM imaging, which uses a fixed exposure time for each pixel regardless of image features. Instead, the team developed an event-based detection system that measures the time taken to detect a set number of electron scattering events. This approach allows for more efficient image building, as Lewys Jones, lead researcher, explains: "Our approach reduces the overall dose of radiation needed to produce high-quality images, eliminates the excess dose that was only providing diminishing returns, and avoids causing unnecessary damage to the sample."

The team's mathematical theory reveals that the first electron detected at each probing position provides substantial information, with subsequent hits offering diminishing returns. This insight led to the development of Tempo STEM, a patented technology that incorporates a high-tech "beam blanker" to shut off illumination at peak imaging efficiency.

Jon Peters, the study's first author, highlights the significance of this advancement: "We tend to think of electrons as relatively mild from a radiation perspective, but when they are fired at a tiny biological sample at speeds of around 75% the speed of light, it's no surprise that they damage these samples."

This innovative method not only improves image quality but also addresses a major challenge in microscopy by reducing the risk of sample damage or transformation. The technology's ability to "blank" or "shutter" the electron beam in nanoseconds in response to real-time events is unprecedented, offering new possibilities for studying sensitive materials and advancing research across multiple scientific disciplines.