20210511 plasma test

Plasma treatment test to achieve best hydrophilic properties (TC)

Different treatments of the plasma cleaner have been tested in order to achieve the best hydrophilic properties. Here is the protocol for hydrophilic treatment:

• place your samples on the window inside the plasma, the faces that need to be treated should be facing up,
• close the chamber, start the pump and wait for the vacuum to stabilize (around .1 mbar),
• open the oxygen bottle (two valves) and set the flowmeter to a value of 60,
• let the chamber fill with oxygen for 5 minutes at least,
• decrease the flow of oxygen to a value of 5 (the bead in the flowmeter is always oscillating a bit, use your integrating eye!),
• while the pressure stabilizes, you can check the plasma parameters:
  • power: maximum (100)
  • time: 10 (up dial should display 0, bottom dial should display 10)
• once the pressure is stable start the plasma,
• when the treatment is finished bring the oxygen flowmeter to 0 (no need to tighten this screw, if it displays 0 then it is closed. Tightening it can damage the flowmeter),
• close the oxygen bottle,
• shut down the pump, start the ventilation,
• once the pressure is balanced with the atmosphere stop the ventilation, open the door and take your samples,
• replace the glass plate inside and start the pump for a few seconds to hold it closed,
• shut down the pump, and the plasma cleaner,
• you are done!

Note: plasma treatment wears out with time and in contact with the atmosphere. To achieve best results you can depose a drop of distilled water on one of the inlet/outlet once you chip is closed. If the PDMS is hydrophilic enough the chip should completely fills with water, protecting the plasma.