Abstract

The super hydrophobic, self-cleaning properties of natural species derive from the fine hierarchical topography evolved on their surfaces. Hierarchical architectures which are function-mimetic of the lotus leaf are here described and created from multi-scale hierarchical assembled templates. The first level of hierarchy was a micromachined dome structure template and the second level of hierarchy was added by layering a thin nanoporous membrane such as porous anodized alumina or an ion track etch membrane. The assembled templates were nanoimprinted by a single step process on thermo-plastic films. The wetting angle of the surfaces reached a value of 160 and the self-cleaning behavior was observed. The superhydrophobic behavior remained over 1 year after fabrication, which demonstrates the stability of these polymeric selfcleaning topographies.

No abstract

A soft‐lithography technique is used to fabricate a microfluidic device with very unique dome‐shaped structures (see image), which are essential for high‐efficiency immobilization and patterning of single beads. Immobilization of the microbeads was achieved by physical entrapment of the beads and patterning was performed at a relatively high flow rate. With such features, encoded microbeads can be incorporated into microfluidic devices to carry out biological assays, significantly increasing their multiplexing capability.

A photolithography technique using SU-8 and PDMS was developed to fabricate three-dimensional hemispherical structures. This technique utilized a maskaligner and normal binary coded photomasks to generate hemispherical pits on SU-8, followed by PDMS molding to obtain an array of dome-shaped structures. Using this technique, a microfluidic device was fabricated with a patterning area that consisted of an array of 5 lm wells and dome-shaped structures with 10 lm diameter and 6 lm height. Encoded microbeads, 6 lm in size, were immobilized and patterned in the microfluidic device under flow conditions and a DNA hybridization experiment was performed to demonstrate the incorporation of encoded beads that would enable a high level of multiplexing in bioassays.