This talk will be about flow control on the micro-scale, inside MEMS devices for precisely handling liquids and particles. For electro-wetting systems (in collaboration with CJ Kim at UCLA), where surface tension is modified by electrical actuation, I will describe our two-phase flow modeling efforts and our control algorithms to move liquid packets and steer the particles inside them. For the electro-osmotic PDMS systems designed and fabricated in my lab, I will show models, control algorithms, and experimental results for trapping and steering one and multiple particles, to micrometer precision (a unique capability in our lab). We are now pursuing this project to clean biological samples, separate stem cells, and load quantum dots into devices.