Control of Micro-Scale Systems

On the macro scale, feedback control is routinely applied to improve performance and enable new tasks in complex and uncertain systems operating in noisy environments. Our lab has focused on applying feedback control ideas to systems on the micro scale. Here we show how control methods can improve existing performance in the UCLA lab-on-a-chip electrowetting system and can create entirely new capabilities in our 'micro fluidic tweezers' cell steering devices.In the Electro-Wetting-On-Dielectric (EWOD) system developed at UCLA by CJ Kim, a grid of electrodes is used to locally change surface tension forces on liquid droplets. By choosing the electrode firing sequence it is possible to move, split, join, and mix liquids in the droplets.

Nanoventions has developed a number of low-cost, complex micro-optic polymer film and particle products that provide optical for the second example; we show how feedback flow control can enable particle steering in cheap, handheld micro-fluidic systems using real time vision feedback and routine electro-osmotic actuation. Here we create temporally and spatially varying flow fields that carry all the particles along their desired trajectories. We have demonstrated flow steering of many particles at once both in simulations and in experiments