Hong, Ikjun; Hong, Chuchuan; Anyika, Theodore; Zhu, Guodong; Ugwu, Maxwell; Higginbotham, James N.; Franklin, Jeffrey L.; Coffey, Robert; Ndukaife, Justus C. (2026).听.听Light: Science and Applications, 15(1), 180.听
This study presents a new technique for analyzing individual nanoparticles鈥攅xtremely small particles used in fields like medicine and environmental science鈥攎ore quickly and thoroughly than before. Understanding the size, shape, and chemical makeup聽of single nanoparticles is important because even tiny differences between particles (called聽heterogeneity) can affect how they behave, for example in drug delivery or pollution tracking. However, current methods often have drawbacks such as being slow, analyzing only a few particles at a time (low throughput), or causing particles to stick to surfaces and become difficult to study.
To address these challenges, the researchers developed a new system called聽Interferometric Electrohydrodynamic Tweezers (IET). This platform combines several advanced techniques into one setup: it can聽trap nanoparticles in place using fluid and electrical forces, visualize them using聽interferometric scattering imaging聽(a sensitive method that detects tiny particles by how they scatter light), and determine their chemical composition using聽Raman scattering聽(a technique that identifies molecules based on how they scatter light at specific energies). Unlike traditional laser-based trapping methods, which can take minutes per particle, the IET system can trap and analyze a nanoparticle in just a few seconds. It also works effectively even when particles are present at very low concentrations, where other methods struggle.
The researchers demonstrated the system by successfully analyzing both synthetic polymer nanoparticles and聽extracellular vesicles (EVs)鈥攕mall biological particles released by cells鈥攚hile they were still suspended in liquid. Overall, this new platform offers a fast and efficient way to study individual nanoparticles in detail, which could improve research and applications in areas like nanomedicine, environmental monitoring, and beyond.
Fig. 1: Working principle of the Interferometric Electrohydrodynamic Tweezers (IET) system.
a聽Schematic view of the IET system capable of rapid parallel trapping of multiple particles and label-free interferometric imaging.听b聽Illustration of the working principle and experimental setup of the IET system. Nanoparticles are rapidly transported by in-plane AC electro-osmotic (ACEO) flow and trapped at the nearest stagnation zones. Forces acting on the particles include FACEO, the drag force from ACEO flow, and Fs, the particle surface interaction force. Optical signals involved are Escat, the scattered electric field from the particle; ERaman,聽the Raman signal from the particle; and Etrans, the transmitted light after passing through the thin gold film. Optical components include: DM the dichroic mirror, BPF the band-pass filter, and LPF the long pass filter