Article: Schein, P; Ashcroft, CK; O’Dell, D; Adam, IS; DiPaolo, B; Sabharwal, M; Shi, C; Hart, R; Earhart, C; Erickson, D; (2015) “Near-Field Light Scattering Techniques for Measuring Nanoparticle-Surface Interaction Energies and Forces”, Journal of Lightwave Technology, 33 (16):3494-3502
Abstract: Nanoparticles are quickly becoming commonplace in many commercial and industrial products, ranging from cosmetics to pharmaceuticals to medical diagnostics. Predicting the stability of the engineered nanoparticles within these products a priori remains an important and difficult challenge. Here, we describe our techniques for measuring the mechanical interactions between nanoparticles and surfaces using near-field light scattering. Particle-surface interfacial forces are measured by optically “pushing” a particle against a reference surface and observing its motion using scattered near-field light. Unlike atomic force microscopy, this technique is not limited by the thermal noise, but instead takes advantage of it. The integrated waveguide and microfluidic architecture allow for high-throughput measurements of about 1000 particles/h. We characterize the reproducibility of and experimental uncertainty in the measurements made using the NanoTweezer surface instrument. We report surface interaction studies on gold nanoparticles with 50 nm diameters, smaller than previously reported in the literature using similar techniques.
Funding Acknowledgement: Cornell University under the U.S. Department of Energy Office of Basic Science [DE-SC0003935]; Optofluidics under NSF [1151966, R44ES02559902]
Funding Text: The theory developed in this work was done at Cornell University under the U.S. Department of Energy Office of Basic Science under Grant DE-SC0003935. The device fabrication and design work was done by Optofluidics under NSF award 1151966. The majority of the experimental work shown in this paper was done at Optofluidics under NIH Award R44ES02559902. This work was equally contributed by Perry Schein and Colby K. Ashcroft.