Eur. Phys. J. E (2009) 28: 113-123
https://doi.org/10.1140/epje/i2008-10414-4

Regular Article

Measuring colloidal forces with the magnetic chaining technique

¹ Center for Soft Matter Research, New York University, 4 Washington Place, 10003, New York, NY, USA
² Laboratoire de Physico-Chimie Théorique, ESPCI ParisTech, CNRS UMR 7083, 10 rue Vauquelin, 75005, Paris, France
³ Laboratoire Colloıdes et Matériaux Divisés, ESPCI ParisTech, UPMC, CNRS UMR 7612, 10 rue Vauquelin, 75005, Paris, France

^* e-mail: dreyfus@nyu.edu

Received: 30 October 2008
Published online: 12 January 2009

Abstract

In 1994 Leal Calderon et al. (Phys. Rev. Lett. 72, 2959 (1994)) introduced the magnetic chaining technique to directly probe the force-distance profile between colloidal particles. In this paper, we revisit this approach in two ways. First, we describe a new experimental design which allows us to utilize sample volumes as low as a few microliters, involving femtomoles of surface active macromolecules. Secondly, we extensively describe the characterization and preparation of the magnetic colloids, and we give a quantitative evaluation of performance and resolution of the technique in terms of force and interparticle separation.