Notes from 4.6.2012 meeting

Notes from 4.6.2012 meeting

Combination vacuum/electrostatic sampler. This is method of impaction onto a charged electrostatic surface. Commercial model here: http://microbiodetection.com/resources/BrochSass3100eng.pdf. Unit weighs ~6 lbs, will operate at -40 C, uses a rechargeable battery, and sucks air at 120 L/min. This seems like a viable, but expensive option. 

Rotarod. Specifically designed to collect pollen samples at lower altitudes. Sticky tape on a rotor. Pollen and fungal spores on the tape are identified under the microscope. (http://www.ag.ndsu.nodak.edu/ndagres/ spring98/ar10598.htm#Table)

Can we use something with more surface surface area with the rotarod? Glass wool is a good option because it will hold up to the temperature and pressure changes, but that is hard to extract DNA from. We need to be able to elute and bead-beat. Could we use the same solvent that they are using to get cells off of?

What about a giant rotor?

To do. Jess & Ann need to send Oliver a button sampler (will ship 4.13.2012).  They will make a fan mock-up. Look for adhesive or gel that is compatible with low temperatures and maintains cells to use with a rotarod or other impaction-type device. Or try glass wool. Or filter that is held up by a grill. Vaseline on blades of the fan (smear on adhesive).

Relevant Information.

Similar project at CSU-Pueblo 

High-Altitude Bacterium Retrieval Design Project

- $700 budget

- design device to collect viable microbes from 90,000 -100,000 feet

Paper detailing the design and testing of an electrostatic sampling device

Collection of airborne microorganisms by a new electrostatic precipitator

Bacteria cultured from samples collected along an altitudinal gradient using a cryosampler

Microorganisms cultured from stratospheric air samples obtained at 41 km

Design Day 1 Follow-up

1) What are the pressure and temperature differentials between the surface and the altitudes we're interested in sampling at?

2) What are the specifications for our button sampler vacuum pumps?

• NiMH battery
• operating temperature range: 0 to 45 C
• altitude: "Do not use pump beyond 7500 ft"
• 12 hrs at 2000 ml/min
• up to 30 inches water back pressure

3) What are the specifications for the filters we've been using in the button samplers. Does the Mixed cellulose ester (1.2 um) - we have used these with the button sampler

• burst strength: > 10 psi
• porosity: 74-77%
• maximum working temperature: 130 C

Cellulose nitrate (0.2 um) - we have used these with larger pumps

• burst strength: > 2 psi
• porosity: 66-84%
• maximum working temperature: 80 C

*** I have not been able to find specific information effects of low temperatures on pore size.
5) We need a way to sample a huge volume of air with no pressure differential. We should look into methods other than filtration for collecting cells, maybe impaction onto foams or other porous materials that particles could stick to. For example glass wool (but touch for bead beating), furnace for houses, 'open cell foam', or polyurethane foam. Think about difference between impingement & impaction.


Impaction onto porous surfaces is a good option and one that we have some experience with. We have used gelatin filters with large pore sizes to trap microbes. Cells end up stuck to the sticky gelatin. The large pore size of the "filter" allows for a higher flow rate.


6) Another way to avoid "sucking" is to explore "pushing" air through a filter. We would need 3-4 psi. What about using a cooling fan harvested from used computer can run off a 9V battery (see image below). Can we use this to move air through a filter? Or onto a surface? We could put these blowers in series. Another idea is a brushless DC blower (a larger) or a "squirrel cage blower" fan.

Design Day 1

Today Ann and Jess visited the UO Machine Shop crew to talk about sampling microbes from balloons. Below are some of the ideas and question that came out of this visit. We will be filling in as much as possible this week!

1) What are the pressure and temperature differentials between the surface and the altitudes we're interested in sampling at?
2) What are the specifications for our button sampler vacuum pumps?
3) What are the specifications for the filters we've been using in the button samplers. Does the pore size change at low temperatures?
4) We should consider tiny altimeters used with models rockets! These could be useful for measuring altitude and as a switch for sampler. Check these out - http://www.sigmarockets.com/blog/2012/02/using-electronic-altimeters-for-model-rockets/
5) We need a way to sample a huge volume of air with no pressure differential. We should look into methods other than filtration for collecting cells, maybe impaction onto foams or other porous materials that particles could stick to. For example glass wool (but touch for bead beating), furnace for houses, 'open cell foam', or polyurethane foam. Think about difference between impingement & impaction.
6) Another way to avoid "sucking" is to explore "pushing" air through a filter. We would need 3-4 psi. What about using a cooling fan harvested from used computer can run off a 9V battery (see image below). Can we use this to move air through a filter? Or onto a surface? We could put these blowers in series. Another idea is a brushless DC blower (a larger) or a "squirrel cage blower" fan.
7) For power - what about using solar cells?