Abstract
We have successfully demonstrated a passive microfluidic chip that can perform rate-switchable and precisely-timed pumping in a programmable manner. A PDMS diaphragm powered by osmosis is employed to provide the desired volumetric displacement for microfluidic pumping. Regulated by integrated time switches, the diaphragm is actuated alternatively to realize a time-varying pumping pattern. Meanwhile, vacuum generators with dedicated check valves and breather valves are employed to realize the priming of fluidic samples. The programmable micro-chip is composed of functional polymeric materials. With an effective permeating area of 10.6 mm 2 , a constant osmotic pumping rate of 9.3 nl/s is achieved. It is demonstrated that the proposed scheme can be programmed to realize 30-second constant pumping alternated with 225-second pause, which could be readily tailored to realize desired time-varying delivery profile. Copyright © (2013) by the Chemical and Biological Microsystems Society All rights reserved.