Setting up climate shock bioassay - (Oct/01/2013 )

Hey ther, firsttime poster on this forum, but thougth i would browse for ideas. 

Me and a associate are putting up a bioassay, where we wan't to subject some larvae for specific temperatureranges for specific amounts of time. We need a programmable device that has a range between +25 to -20 degrees celcious. The twist is, that it needs to be fully programable, both the rate of wich cooling occures, the time it'll stay at a specific temperature, the rate of which re-heating occurs and the stand-by temperature. 

A major issue is, that for some of the temperatures, we only wish to subject our specimens to certain temperatures for exactly 60 seconds (+/-5), this is very hard (read. impossible) to control in ordinary climate chambers. 

The speciemns we work with, are larve of the common cabbageflea, which overwinters in the stem of cabbage, so the capacity of whatever aparatus you may sugest, needs to be at leas large enough to house a 6 x 15 cm sealed cup containing the samples.

Any ideas would be apreciated, even unconventional ideas

Have you looked into peltier cooled devices?  Would it be possible to put the larvae into smaller tubes (e.g.0.2 or 0.5 ml tubes) and then heat/cool them in a standard PCR machine?

Unfortunatley not. we considdered the option, but cutting out the larvae from it's hostplant will either kill it, or stress it severly. Plus it's partially a behaviorial study, if they survive, we'll try to determine wheter they acted activly to the change in climate, so it's urgent that they have sufficient space.

Even so, we don't have acces to PCR machines that'l drop to a minus 20 degress celcious.

True - most PCR machines won't do that, I misread and thought you were looking for +20-+25 range...

I still think that a peltier controlled device will be the best bet, though you will probably have to get a custom device made.

I was afraid it had to come to that. We have funds, yet a customamade device is usualy quite expensive

The first parts ("fully programable, both the rate of wich cooling occures, the time it'll stay at a specific temperature, the rate of which re-heating occurs and the stand-by temperature") every good programmable climate chamber or cabinet should do.

The second I also would say is impossible as the delay of heating the air which then heats plant parts and then the larvae to get a higher temperature would not work as there's too much air and other material that has to be heated and this will cost mire than the desired times.

Perhaps you can develop something like a sleeve or cuff which is fitted around the plant stem and contains a cooling/heating device (e.g. peltier elements) or the tubes/pipes of a device that leads heat or cold directly to the sleeve (also a peltier controlled device would fit, as it's fastest).

Also you need an external sensor for temperature measurement directly at the larvae's place (e.g. a thermocouple from a data logger) to be sure that at this place the parameters are okay.

Hobgoblin, you may have given me an idea... I think we have a couple of broken cliamtelockers with working elements... i think i may be able to retrofit the elemnts in such a way,that the cabbageleafs is stuck between them, without crushing it. thus the temperature (the voulume of air which needs to heated/cooled) should be easier to control, and more responsive... I'll have to go do some serious thinking about this... oh, and we have a ton of different thermologgers, so that's no real problem :-) ... thanks for your inputs so far. please, keep them comming

You think it'll be possible to buy programable cooling plates anywhere?