Photoinduced Reversible Change of Fluid Viscosity

Sakai et al, "Photoinduced Reversible Change of Fluid Viscosity"
J. Am. Chem. Soc., 127 (39), 13454, 2005.

Using a modified azobenzene molecule, the author demonstrate a fluid in which the viscosity may be switched reversibly from high viscosity to low viscosity, using visible/ultraviolet light to flip a bond from trans to cis conformations. This could form the basis for a neat science "magic" trick.