NYC Gazette

Dr. Fredy Zypman, director of the Katz School’s M.A. in Physics, along with recent graduates, has developed an algorithm that uses scanning force microscopy to measure electric charges on nanoscale rings. This innovation promises to enhance charge measurement precision and holds potential applications in nanotechnology, biosensing, quantum computing, and materials science.

Their study titled “Theory for Measuring Electric Charge Density of a Ring from Scanning Force Microscopy,” published in the American Institute of Physics Advances, examines how a charged ring interacts with the tip or sensor of a scanning force microscope (SFM). SFM is a precise technique that records tip movements as it scans microscopic structures, analyzing these movements to identify forces such as electrostatic ones.

The researchers have devised a method to convert tiny forces measured by the microscope into charge values within a ring. These forces can be detected with current technology. Their method acts like a bridge between charge spreading on the ring and the forces measured by the microscope.

“This research has immediate use to designing smaller and more efficient devices, detecting biological molecules with unprecedented precision, and understanding and manipulating the properties of new materials,” said Moshe Gordon, co-author of the paper who graduated this year with a master’s in physics from the Katz School.

A significant breakthrough of their study is its method of breaking down uneven charge distribution into simpler components called multipoles. Using data from electrostatic forces, the algorithm calculates these multipole values to accurately determine how charge spreads across the ring.

“This approach is particularly useful because multipoles play a major role in electrostatic interactions at microscopic scales,” said Yonathan Magendzo, co-author of the paper who graduated from YU with a B.A. in physics in 2023.

Measuring charge density with nanometer-scale resolution has broad implications. Charged rings are found in various systems including molecular pumps, biosensors, and nano-optoelectronic devices:

- Biomedicine: Electrically charged molecular rings are crucial in peptide synthesis and bio-piezo materials used for tissue engineering.

- Quantum Computing: Charged nano-rings are promising candidates for qubit storage where precise charge measurement is critical.

- Advanced Materials: Understanding charge effects in nanostructures can enhance nanoelectronics and biomaterials design.

“Carbon, gold and silver nano-rings synthesized through various techniques stand to benefit from this method,” said Benjamin Goykadosh, co-author of the paper who graduated from Katz School with an M.A. in physics in 2022. “Charge properties play a pivotal role in their applications, and this algorithm offers a new tool to explore and optimize these properties.”

Current techniques like Kelvin probe force microscopy face limitations in accuracy and spatial resolution. This study offers a powerful tool for dissecting electrostatic interactions at nanoscale levels.

“Our work contributes to understanding charge-driven processes from self-assembly in large molecules to electronic device performance,” said Dr. Fredy Zypman, senior author of the paper and professor of physics. “By enabling precise charge mapping, the algorithm opens doors to new scientific discoveries and technological innovations.”