Compact 3D microfluidic channel structures embedded in glass fabricated by femtosecond laser direct writing

We demonstrate rapid fabrication of complex three-dimensional (3D) microfluidic channels with lengths up to ~6.0 cm within a tiny volume down to ~80 nl in glass substrates by femtosecond laser direct writing, which, to the best of our knowledge, is the longest microfluidic channel directly embedded in glass by femtosecond laser microprocessing. The fabrication mainly includes the following two steps: (1) formation of hollow microfluidic channels in porous glass by scanning a tightly focused femtosecond laser beam inside a porous glass immersed in water; and (2) postannealing of the fabricated porous glass sample at ~1150 °C for consolidation of the sample. The unique 3D capability of our technique allows construction of extremely compact microfluidic devices and systems.