Rapid prototyping of three-dimensional microfluidic mixers in glass by femtosecond laser direct writingElectronic supplementary information (ESI) available: Details of the mesoporous glass preparation, the numerical simulations of mixing results, fabrication of 3D helical microchannel and 3D micromixer, movie of the direct writing process. See DOI: 10.1039/c2lc21015k

The creation of complex three-dimensional (3D) microfluidic systems has attracted significant attention from both scientific and applied research communities. However, it is still a formidable challenge to build 3D microfluidic structures with arbitrary configurations using conventional planar lithographic fabrication methods. Here, we demonstrate rapid fabrication of high-aspect-ratio microfluidic channels with various 3D configurations in glass substrates by femtosecond laser direct writing. Based on this approach, we demonstrate a 3D passive microfluidic mixer and characterize its functionalities. This technology will enable rapid construction of complex 3D microfluidic devices for a wide array of lab-on-a-chip applications. We demonstrate femtosecond laser direct writing of a 3D microfluidic mixer embedded in a glass substrate with excellent mixing performance.