Integration of Silica Aerogels in Microfluidic Chips

This paper reports a method to integrate silica aerogels monolithically in microfluidic chips. Silica Aerogel is a highly porous bulk material. The gel was synthesized from tetraethyl orthosilicate by a sol-gel process. Polyethylene glycol and an extended aging period were used to strengthen the matrix minimizing gel shrinkage. This technique allows alcogel structures with high strength and stiffness that withstand high pressure during the subcritical drying process. Hexamethyldisilazane provides for hydrophobizing and prevents the formation of siloxane bonds during the drying process. The resulting transparent aerogels reach porosities of 85%, pore diameters around 50 nm and contact angles of 136°.