Maryland researchers use microscopic twist to image 2D materials

Researchers at the University of Maryland have developed a new method to image the surface of two‑dimensional materials with unprecedented resolution by rapidly twisting a microscopic tip back and forth. The technique, demonstrated in a recent study, allows scientists to see how these thin sheets flex when exposed to infrared light, revealing tiny changes that were previously invisible. The work was carried out in the university’s nanoscience lab and was published in a peer‑reviewed journal this week.

Two‑dimensional materials, such as graphene and molybdenum disulfide, are only one atom thick but have extraordinary electrical, optical and mechanical properties. Engineers want to use them in flexible displays, sensors and next‑generation computers. A key challenge is understanding how tiny strains and ripples in the material affect its performance. Traditional imaging tools can disturb the sample or lack the spatial resolution needed to capture these subtle deformations. By twisting a probe tip at high speed, the researchers create a mechanical “tick” that senses the minute flexing of the material’s surface, producing images at the nanometre scale.

In the experiment, the tip was moved back and forth at frequencies above 10 kilohertz while a laser beam in the infrared range illuminated the sample. The tip’s motion was recorded with a piezoelectric sensor, and the data were converted into maps of strain and topography. The team applied the method to a graphene sheet and observed a network of strain fields that matched predictions from theoretical models. Dr. Maria Lopez, the study’s lead author, said the resolution is “about 20 times better than what we could achieve with conventional atomic‑force microscopy.” The technique also measures how the material’s surface height changes by as little as 0.1 nanometres, a sensitivity that could help identify defects before they cause device failure.

The researchers plan to extend the method to layered heterostructures, where different 2D sheets are stacked to create new electronic states. They also aim to integrate the twisting probe into commercial microscopes, making the technology accessible to other labs. If successful, the technique could accelerate the design of flexible electronics, improve the reliability of nanoscale sensors, and deepen our understanding of how light and strain interact in the thinnest materials known.