Previous work has shown that single-beam gradient traps are unable to trap high index particles in fluids
where the index contrast is large. However, by changing the refractive index of the surrounding medium to
more closely match the index of refraction of the particle, trapping of high index particles is possible. We
report preliminary efforts to trap high index glass particles having indices of about 1.9. The experimental
trap stiffness data of polystyrene beads with radius 1.8 and 10 µm suspended in water is presented. The
next step is to trap high index particles as well as determine the trap stiffness for those particles having
diameters in the 3-10 μm range suspended in fluids having refractive indices in the range of 1.4 to 1.6.