An array of transportable particle sets is used in a microfluidic device for performing chemical reactions in the microfluidic device. The microfluidic device comprises a main channel and intersecting side channels, the main channel and side channels forming a plurality of intersections. The array of particle sets is disposed in the main channel, and the side channels are coupled to reagents. As the particle sets are transported through the intersections of the main channel and the side channels, reagents are flowed through the side channels into contact with each array member (or selected array members), thereby providing a plurality of chemical reactions in the microfluidic system.