Liquid Handling in a Microfluidic Chip by Micro-Aspiration

We report on a new method to handle fluids in microfluidic systems by using both micro- aspiration and PDMS valves. Multilayer soft lithography technique has been used to fabricate microfluidic circuit and micro-aspiration network. We introduced micro-aspiration areas to locally create vacuum in the microfluidic network. The induced pressure differences can drive confined liquid into motion. This allowed us to fill chambers, form droplets and displace droplets in channels without any other external injection apparatus. We describe the principle and the operation of this method. Finally, we discuss a possible application of this method in the field of protein crystallization.