Monolith Wetting with Ethanol Vapors
Summary
I need to replace the function of my breath to get water into the femtoliter sized cavity of the monolithic device. I achieve this using a small stream of ethanol vapor as a precursor, and then replace the ethanol with water. Once the chips are wet, they should be reasonably stable until they can be installed in a device.
Setup
I’m using a cheap $10 vaporizer from bed/bath/beyond, and tubing (ID = ring finger). The vaporizer pulses out at a high rate in spurts, but guiding the stream with the tubing smooths out rate of application. Small air currents can disrupt the stream, so I applied it manually during experiments. Condensation forms in the tube. The video above shows water vapor being passed over a chip, which is much easier to see than the ethanol vapors. The light from the microscope heats up the substrate and causes the small amount of fluid condensed on the surface to eventually evaporate.
Wetting Events
Water Vapor from Breath
Ethanol
This chip was previously wetted with H20 vapor, but not all channels were wetted.
These chips have never been exposed to vapor of any kind.
Water on dried-out ethanol substrate
Ethanol, then Water immediately
I achieved this combination by manipulating the filter stick in the vaporizer. It soaks in the liquid, so i immersed half the stick in DI water, and then the other half in Ethanol.
Ethanol Prewet:
Water wetting afterwards:
It seems we have a candidate for a more repeatable wetting process, using ethanol vapors, and then diluting out the ethanol with water.
I’ve been using a similar vaporizer for membrane transfers using water vapor. Never tried ethanol, but should be straightforward. We have 6 of the well design chips left. A co-op student will be trying with the autoclave this week, and I will tell him to roll this into his work as well.