Thursday, June 28, 2012

I am Jeff Wright and I teach physics at Louisville Male High School.   During this fellowship I have been working with Dr. McNamara and researching Knudsen pumps.  These pumps create a pressure difference across a membrane with nanopores in them.  These small pores do not allow molecules to collide as they pass through, so if a temperature gradient is created on either side of the membrane, gases will flow from the more dense cold side of the membrane to the less dense hot reservoir.  Alex, a Speed School student, is trying to develop a Knudsen pump which will administer medicine without electricity and just using body heat to create the temperature difference.  Fiaz, a doctoral student, is trying to use thermal electrics which get hot on one side and cold on the other, as the pump membrane.
I have constructed several Knudsen pumps using different materials for membranes.  Now that the poster has been constructed, this week I will be writing lesson plans which include a simulation in which the students walk near a door opening symbolizing hot and cold gas molecules and the door a nanopore in a membrane.  I also have a computer simulation from PhET which is a good model.  I now have to find inexpensive materials the students can use to build the Knudsen pumps.   This may include concrete and agar for membranes,  cola cans for heat sinking aluminum, light bulbs for heaters,  rubber cement or caulk for glue.   I am not sure what to use for tubing yet and it is $250 a roll.   Surprisingly the technology is not a problem because the Gas Pressure sensors from Vernier which connect to Lab Pro and Lab Quest seem to measure these small pressures well enough to see a pressure drop.  Some tubing taped to a ruler has been adequate enough to use as a flow rate monitor.  I just have to start testing all of these "home made" supplies one at a time to see if they will work in the classroom.

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