Automated microfluidic sample stream position control for on-chip selective drug delivery

In this paper we present a novel microfluidic system which is able to automatically control the position of a hydrodynamically focused non-coaxial sample stream within a microchannel for on-chip applications such as selective drug delivery. A colored sample stream is optically detected by a high definition camcorder mounted on a microscope (approximately 2 μm resolution). To determine sample stream position and width, the frames are grabbed and processed. To position the sample stream, volume driven syringe pumps are actuated via a PC implementing two different controllers, PI and Fuzzy. The microfluidic system has been identified by a non-linear ARX model. Closed-loop time domain experiments to accurately position a 25 μm wide sample stream within a 160 μm wide channel have been successfully carried out with both control systems.