I wish I had a schematic of the corona discharge unit mentioned; then I could replicate it. It is quite small, with a working area of about 20x20 cm that seems to be made of about 1 cm thick Teflon(?). It has a roller that has the anode(?). The roller is used by hand and is about 3 cm of diameter and of white plastic that didn't seem like Teflon. Hard to say. The anode(?) is inside the roller.
It has a wattage meter from 0 to 200 watts. It showed approx. 20-40 watts during the treatment. It also had a knob called "treatment level" from 0 to 10. Level 5 wasn't enough to make PET hydrophilic but 8 was . After treatment, a small amount of water forms a very even, thin layer on the sheet. A huge difference compared to untreated areas as I run water over the sheet.
I built a HV probe so I could measure the output from the unit with oscilloscope and then replicate it. But I don't know when we'll get next chance to see and use the machine at the lab.
We still use the same blade we made when we started; I have posted pictures of it: http://www.apug.org/forums/forum205/...tml#post866943 . The gap is about 200 um. I tape the PET sheet on the glass plate, use a 50 ml syringe to squirt some emulsion in the front of blade and give it a go. Then I put the glass plate + the sheet in a refrigerator for a minute or two and then let dry for 24 hours at room temp. I use some masking tape to secure the sheet on the glass plate so it won't curl during drying.
Thank you everyone for encouraging words!