12-02 :: February/March 2012
nanotimes News in Brief
Rapid Prototyping // 3D Microfluidic Mixer by Femtosecond Laser Direct Writing
esearchers at State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and
Fine Mechanics, Chinese Academy of Sciences (SIOM) developed a new technique to fabricate micro-channels in glass with nearly unlimited lengths and with arbitrary geometries. The main fabrication process includes two steps: (1) direct formation of hollow microchannels in a mesoporous glass substrate immersed in water by femtosecond laser ablation; and (2) postannealing of the glass sub- strate at 1,150° C (2,102° F). This consolidates the nanoscale pores by causing them to collapse. Howe- ver, the fabricated microchannels survive due to their larger size.
Based on this newly established technique, a passive microfluidic mixer consisted of geometrically com- plex 3D microchannels was demonstrated, as illustra- ted in Figure 1a. The superior mixing efficiency of the 3D mixer is also confirmed by numerical simulations as well as mixing experiments, as shown in Figures 1b and 1c, respectively. The dimensions of channel can be easily changed by controlling the machining parameters, such as the numerical aperture of objective, the laser pulse energy and the translation speed. To show this capability, a 3D microfluidic lantern composed of 3D microchannels with different sizes was fabricated by this technique.
When either fluorescein sodium solution or Rhoda- mine B solution was injected into the microchannel and excited by a laser operated at 490nm or 540nm wavelengths, the lantern produced either green or red colors, as shown in Figures 1d and 1e, respec- tively. The technique is promising for a broad spec- trum of microfluidic applications based on compact and complex 3D microfluidic networks in the future.
Yang Liao, Jiangxin Song, En Li, Yong Luo, Yinglong Shen, Danping Chen, Ya Cheng, Zhizhan Xu, Koji Sugioka and Katsumi Midorikawa: Rapid prototyping of three-dimen- sional microfluidic mixers in glass by femtosecond laser direct writing, In: Lab on a Chip, Vol. 12(2012); Issue 4, January 09, 2012, Pages 746-749, DOI:10.1039/C2L- C21015K: