Microfluidic systems including three-dimensionally arrayed channel networks

Abstract

The present invention provides, in certain embodiments, improved microfluidic systems and methods for fabricating improved microfluidic systems, which contain one or more levels of microfluidic channels. The inventive methods can provide a convenient route to topologically complex and improved microfluidic systems. The microfluidic systems provided according to the invention can include three-dimensionally arrayed networks of fluid flow paths therein including channels that cross over or under other channels of the network without physical intersection at the points of cross over. The microfluidic networks of the invention can be fabricated via replica molding processes, also provided by the invention, utilizing mold masters including surfaces having topological features formed by photolithography. The microfluidic networks of the invention are, in some cases, comprised of a single replica molded layer, and, in other cases, are comprised of two, three, or more replica molded layers that have been assembled to form the overall microfluidic network structure. The present invention also describes various novel applications for using the microfluidic network structures provided by the invention.

1 . A method for forming topological features on a surface of a material comprising:
 exposing portions of surface of a first layer of photoresist to radiation in a first pattern;   coating the surface of the first layer of photoresist with a second layer of photoresist;   exposing portions of a surface of the second layer of photoresist to radiation in a second pattern different from the first pattern; and   developing the first and second photoresist layers with a developing agent to yield a positive relief pattern in photoresist, the positive relief pattern including at least one two-level topological feature having at least one cross-sectional dimension not exceeding about 500 μm, which two-level topological feature is characterized by a first portion having a first height with respect to the surface of the material and a second portion, integrally connected to the first portion, having a second height with respect to the surface of the material.