Scalable, non-contact determination of electric properties of nanostructures via electro-rotation in water solution

Breakthroughs in nanotechnology have enabled the large-scale fabrication of nanoparticles with varied compositions and structures. Yet, evaluating their electrical conductivities remains challenging due to high volume and individual variability. We report a rapid, non-contact, and parallel method to characterize longitudinal nanostructures, including insulators, semiconductors, and conducting metal oxides by using MoO3, MoS2/MoO2, and MoS2 nanoribbons, produced at different fabrication stages, as a model system. Leveraging our semi-quantitative model based on Maxwell–Wagner and electrical double-layer polarization, electric conductivities of various nanoparticles are determined from their distinct electro-rotation behaviors in water, spanning six orders of magnitude. The results agree well with standard four-probe measurements. The technique, measuring multiple nanoparticles at once, without the use of electrical contact, can be easily scaled up for parallel determination of particles' electric conductivities. These findings highlight a nondestructive, rapid, and simple characterization method promising to bring nanomaterials closer to practical applications in electronics, optics, sensing, catalysis, and robotics.