Novel method and device for high resolution and quantitative sizing of nanoparticles suspended in liquids

J.E. Farnsworth, J.H. Scheckman, J.S. Higgins, K. Erickson, E. Willis, T. Johnson, R. Caldow
TSI Incorporated, US

Keywords: SMPS, nebulizer, colloids, slurry, characterization

Summary:

This paper highlights a new method for sizing nanoparticles in liquid suspensions. It builds off of research and optimization done by CT Associates (Eden Prairie, MN) over the past 3 years which recently resulted in commercialization of the technique (TSI Models 3485 and 3985). This will be the first presentation in which results from the commercial device are presented. The enabling technology, Scanning Mobility Particle Sizing (SMPS), is a well-established gas-phase sizing technique typically used for measuring airborne particle size distributions. SMPS uses particle mobility instead of light scatter (used by DLS, laser diffraction and OPCs) to obtain size and therefore its sizing capabilities are not influenced by the optical properites of the material. This yields high resolution sizing and a <5nm lower size limit. When combined with a new Nanoparticle Nebulizer for liquid-phase sizing, absolute number concentration is also obtained. Applications include liquid filter characterization; sizing of CMP slurries, medical nanoparticles, and biomaterial in liquids; waste water analysis, etc. The paper presents results from beta units used in semiconductor and filter testing applications. Limitations of the technique will also be discussed.