Viscosity measurement using a rotating laser-trapped microsphere of liquid crystal

• Published in: Europhysics letters Vol. 73; no. 5; pp. 800 - 805
• Main Authors: Murazawa, N, Juodkazis, S, Jarutis, V, Tanamura, Y, Misawa, H
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.03.2006; EDP Sciences
• Subjects: 42.70.Df; 83.85.Ei; 83.85.Jn
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/epl/i2005-10457-7

We demonstrate that the viscosity measurement by a spinning laser-trapped liquid-crystal microsphere depends on the surface tension and hydrophobicity of sphere's material. A reduction of the viscous drag was observed for the hydrophobic E44 liquid-crystal droplets even at low surface tension, while a reduced surface tension caused an increased drag in the case of 5CB microspheres. The importance of the non-slipping boundary condition and light propagation throughout the laser-trapped microsphere in the viscosity measurements by a spinning microsphere (Bishop A. I. et al. , Phys. Rev. Lett., 92 (2004) 198104) is discussed.