Contamination of PDMS microchannels by lithographic molds.

By use of synchrotron X-ray fluorescence and Rutherford backscattering spectrometry, we show the SU-8 soft lithographic process contaminates PDMS. Residues of the antimony containing photoinitiator are transferred from the master mold to the surface of PDMS, uncontrollably intensifying the surface potential, leading to electroosmotic flow variability in PDMS microfluidic devices.

A rapid, inexpensive surface treatment for enhanced functionality of polydimethylsiloxane microfluidic channels.

A rapid, inexpensive method using alkoxysilanes has been developed to selectively coat the interior of polydimethylsiloxane (PDMS) microfluidic channels with an integral silicaceous layer. This method combines the rapid prototyping capabilities of PDMS with the desirable wetting and electroosmotic properties of glass. The procedure can be carried out on the open faces of PDMS blocks prior to enclosure of the channels, or by flowing the reagents through the preformed channels.

Unprecedented oxo-titanium citrate complex precipitated from aqueous citrate solutions, exhibiting a novel bilayered Ti8O10 structural core.

Aqueous titanium citrate solutions were prepared from the reaction of citric acid with titanium 2-propoxide in a range of molar ratios. Solutions containing two or fewer citrates per titanium resulted in the slow crystallization of an insoluble titanium oxo-citrate complex. Single-crystal X-ray analysis identified the species as Ti(8)O(10)(citrate)(4)(H(2)O)(12).