We have studied the behavior of nano or micro size composite particles submitted to optical trapping forces and a comparison was made with homogeneous particles of similar dimension. The forces were measured using the power spectrum signal analysis. Most of the results presented were obtained using a lateral effect position sensitive detector (PSD), which allowed the fluctuations of the particle position in the optical trap to be monitored. A 4-quadrant photodiode was also used for the same purpose. We bring clear experimental evidence that the trapping force was increased by a factor of about 2–3 for composite particles made of a colloidal gold core encapsulated in a silica shell, with respect to homogeneous silica or latex beads. These results were discussed in the frame of the various approaches currently used for modeling optical tweezing forces.
Thursday, June 25, 2009
Nanometer gold–silica composite particles manipulated by optical tweezers
Mariela Rodriguez-Otazo, Angel Augier-Calderin and Jean-Pierre Galaup
We have studied the behavior of nano or micro size composite particles submitted to optical trapping forces and a comparison was made with homogeneous particles of similar dimension. The forces were measured using the power spectrum signal analysis. Most of the results presented were obtained using a lateral effect position sensitive detector (PSD), which allowed the fluctuations of the particle position in the optical trap to be monitored. A 4-quadrant photodiode was also used for the same purpose. We bring clear experimental evidence that the trapping force was increased by a factor of about 2–3 for composite particles made of a colloidal gold core encapsulated in a silica shell, with respect to homogeneous silica or latex beads. These results were discussed in the frame of the various approaches currently used for modeling optical tweezing forces.
We have studied the behavior of nano or micro size composite particles submitted to optical trapping forces and a comparison was made with homogeneous particles of similar dimension. The forces were measured using the power spectrum signal analysis. Most of the results presented were obtained using a lateral effect position sensitive detector (PSD), which allowed the fluctuations of the particle position in the optical trap to be monitored. A 4-quadrant photodiode was also used for the same purpose. We bring clear experimental evidence that the trapping force was increased by a factor of about 2–3 for composite particles made of a colloidal gold core encapsulated in a silica shell, with respect to homogeneous silica or latex beads. These results were discussed in the frame of the various approaches currently used for modeling optical tweezing forces.
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