Laser tweezer technique for study of gelation process

Laser tweezer trapping technology has been applied to monitor the bulk local solution viscosity during the sol-gel gelation process. The gelation rate is the same in depth ranges 2-20 microns from the bounding surface. Simultaneously with the laser tweezer study, a micro-viscosity kinetic measurement of the sol-gel process was performed using fluorescent anisotropy and quantum yield measurements. The differences between the bulk- and micro-viscosities obtained in the experiment reflect the intrinsic differences in solution environment sensed by the laser tweezer on the macro level and by other optical techniques within the probe microscopic environment.