Three-dimensional lithographical fabrication of microchannels

With the rapid development of microfluidic systems, there is high demand for fabrication methods for the fluidic components that can be used to realize complex three-dimensional (3-D) geometries, high integration levels, full compatibility with sensing and controlling circuits, and possess batch fabrication capability. In this paper, we propose and demonstrate such a method based on a novel 3-D lithography technique. The method employs commercially available photoresist and standard lithography facilities. Single-level microchannels with micron-size cross sections up to 1.2 mm in length, as well as multilevel channels with unique 3-D structures, have been fabricated using the proposed method. This method allows direct postintegration of microchannels with previously fabricated integrated circuits without etching, bonding or additional material deposition except resist spin coating. Using this method, the fabrication of microchannels can be greatly simplified, and many unique 3-D topologies beyond the ability of current techniques can be obtained.