title: Near-field Light Scattering Techniques for Measuring Nanoparticle-Surface Interaction Energies and Forces.
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 productsa prioriremains 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 thermal noise, but instead takes advantage of it. The integrated waveguide and microfluidic architecture allow for high-throughput measurements of about 1000 particles per hour. 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.
authors: Sibley School of Mechanical and Aerospace Engineering at Cornell University, Ithaca, NY 14853, USA.
authors: Perry
authors: P
authors: Schein
authors: Optofluidics, Inc., Philadelphia, PA 19104.
authors: Colby K
authors: CK
authors: Ashcroft
authors: School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853.
authors: Dakota
authors: D
authors: O'Dell
authors: Optofluidics, Inc., Philadelphia, PA 19104.
authors: Ian S
authors: IS
authors: Adam
authors: Optofluidics, Inc., Philadelphia, PA 19104.
authors: Brian
authors: B
authors: DiPaolo
authors: Optofluidics, Inc., Philadelphia, PA 19104.
authors: Manit
authors: M
authors: Sabharwal
authors: Optofluidics, Inc., Philadelphia, PA 19104.
authors: Ce
authors: C
authors: Shi
authors: Optofluidics, Inc., Philadelphia, PA 19104.
authors: Robert
authors: R
authors: Hart
authors: Optofluidics, Inc., Philadelphia, PA 19104. Contact: Christopher Earhart (ce@opfluid.com).
authors: Christopher
authors: C
authors: Earhart
authors: Sibley School of Mechanical and Aerospace Engineering at Cornell University, Ithaca, NY 14853, USA. Contact: David Erickson (de54@cornell.edu).
authors: David
authors: D
authors: Erickson
keywords: Biophotonics; Force measurement; Microfluidics; Nanoparticles; Optical Waveguides