Spontaneous Liquid Flow in Microfluidic Systems by U V Irradiation of the Hybrid Polymer/TiO_2 Nanorods Channels

摘要

A method for enhancing the surface wettability of PDMS microchannels used in microfluidic devices, is presented. Colloidal TiO_2 nanorods are mixed in a PDMS solution that was used subsequently to realize parallel microchannels, through a replica molding procedure. TiO_2 has the intrinsic capability of increasing dramatically its hydrophilicity upon UV irradiation. Due to this property, incorporating TiO_2 nanofillers into the PDMS microchannels we manage to induce their hydrophobic-to-hydrophilic conversion upon UV irradiation. This conversion is essential for water to fill the microfluidic channels, in contrast to what happens for the non-irradiated nanocomposite or pure PDMS channels, which are characterized by high hydrophobicity and do not allow water to penetrate. The reversibility of the wettability changes permits to the microchannels to recover their original hydrophobicity.