Before pipetting or printing the aqueous metal solutions onto the FTO glass, the surface of the glass should be made hydrophobic (literally translated "water-fearing"), so that solution beads up on the surface, minimizing the spread of the solution. This makes for better resolved, more uniform scans. Several methods exist to achieve this effect, to varying degrees. Some are easier and/or safer than others, providing somewhat reduced hydrophobicity. The choice of method should be based on the techinical abilities of, and resources available to, the SHArKees.
Cleaning Procedures Edit
Alcoholic KOH Bath Edit
Gildevin Jagudajev suggest the use of a caustic bath of saturated potassium hydroxide in isopropanol to clean the glass. Soaking the plate in this solution for 30 minutes followed by rinsing with DI water then absolute ethanol yields clean glass.
Making the Glass Hydrophobic Edit
Ethanol/Methanol Wash Edit
The method suggested by the SHArK User's Manual consists of first washing the FTO glass plate with ethanol and allowing to dry, then using a Kimwipe saturated with methanol to wipe the plate clean.
Methanol Soak Edit
Gildevin Jagudajev has suggested soaking the clean glass plates in methanol for 10 minutes to achieve hydrophobicity.
An more effective, albeit quite more hazardous, method suggested by Gildevin involved soaking the glass in a 6% (v/v) solution of dichlorodimethylsilane in hexanes for 10 minutes. The silylated glass is rinsed with hexanes and dried in a 60°C oven for a least 1 hour; the glass is allowed to cool for 10 minutes prior to use. This method is not generally recommended for high school students. JT Baker rates dichlorodimethlsilane as a "severe" hazard for health, flammability, reactivity, and contact; contact with water produces hydrogen chloride and phosgene. A desiccator and vacuum pump may also be employed to silylate glassware.