inch/min. Measurements of the modulus were calculated from the linear portion between

the stress of 0.2 and 0.5 pounds and recorded.

Preparation of Textured Surfaces

 All textured surfaces were taken from silica wafers with textures etched using

microfabrication technology. Wafers were provided by Chuck Seegert at two etch

depths, 5 |tm and 1.5 |tm. Briefly, silicon wafers were coated with a thin layer of a

photosensitive polymer and then exposed to UV light through a photomask imparting

various 5 |tm patterns onto the photoresist as seen in Figure 3.1.


 A






 5,000 p --25,000 jm


 10,000 mn .....






Figure 3.1 Representation of etched patterns on silicon wafers. Each square side is
10,000 rm long and is made up of 5 [m wide ridges, separated by varying groove depth.
Each square is separated into thirds with the groove depth in each third 5 rim, 10 rim, or
20 rm wide. Square A has ridges 60 rm long with 40 rm in between. Square B has 5
lm square pillars. Square C has 10,000 [m long continuous ridges and square D has 800
rm long ridges with 200 [m smooth space in between.



 After development, the wafer was etched using reactive ion etching to the desired

depth. The 5 |tm deep wafer was patterned here at the University of Florida, and sent to

Unaxis, USA for etching via the Bosch process. The 1.5 |tm wafers were etched in