(73a) Acoustically Driven Microfluidics to Mimick Blood Flow on a Chip

I'll present a novel approach towards the needs of a versatile microfluidic chip-based microfluidic system with unique properties and functionality. Like for microarrays and in contrast to many existing microfluidic technologies, the fluid handling is performed on the flat surface of a programmable chip, where fluidic tracks and functional blocks such as valves, dispensers, mixers, and sensing elements are chemically defined using standard lithographic techniques. The actuation of the fluid, the driving and adressing of the functional elements as well as possible sensors are based on electrically excited mechanical acoustic waves, propagating along the surface of a chip. The combination of such fluidic networks and our unique pumping technology results in fully programmable microfluidic processor chips. The whole system has no moving parts, and is easily fabricated employing standard semiconductor technologies. Moreover, due to the planar nature of the chip all functional blocks are readily accessible from the outside, e.g., by pipettes or spotting robots. This unique feature makes our programmable fluidic processors fully compatible to existing laboratory environments and most any chemical and biological processes and assays.

Typical areas for the application of this novel technology are the hybridization of DNA or proteomic microarrays, nano-titration stages, on-chip polymerase chain reactions, and cell assays, where single cell manipulation at the planar surface of a chip can be performed. Apart from giving a detailed introduction to the basics of our technology we present a variety of different applications, focusing on the simulation of blood flow on a chip. We will present how we built a flow chamber directly on the surface of a SAW-chip. The new approach is used to unravel the initial step of blood clotting, which is mediated by the largest protein in the human plasma, von Willebrand factor (vWF). Studying vWF's dynamics under flow helped to explain how an increase in shear flow can actually lead to an increased in blood platelet adhesion.