headstage overheating the solution?

Hello,

I have just browsed through a paper published in J. Neurosci. where they used MEAs: http://www.jneurosci.org/cgi/content/full/30/8/2871

and I came acrosas this slightly odd paragraph in methods:

"Network recordings. Multielectrode arrays (MEAs) were coated with poly-D-lysineand laminin per the manufacturer's instructions and dispersedcultures were grown as described above. At day in vitro (DIV)7and DIV10, one-third of the medium was removed and replacedwith fresh Neurobasal supplemented with B27 and glutamine. Recordingswere made with the MEA-60 recording system (MultiChannel Systems)with the headstage in an incubator set at 29°C and equilibratedwith 5% CO₂ in room air with no additional humidity. The lower temperature was necessary because the electronics in the headstagegenerate 7°C of excess heat. "

Did anyone else observe this kind of over-heating? Does it depend on the presence of the inserted wire into the heating cannula?

Many thanks for any info about this!

Maksym

Hi Maksym,

I think the issue here is, that they set up the amplifier within an incubator.
So the incubator already heats to 37°C. As our heating element cannot cool down like a Peltier, but just heats, they had to make sure that there was no overheating.
Just switching off that channel would have done the job as well, as the Incubator did the heating...

Thomas

Many thanks, Thomas!

I have another about the heating system: what difference does it make if one removes the wire from inside the cannula? I think it is easier to flush the cannula and to adjust the flow if the wire is out, however I heard that it affects the accuracy of temperature maintanence. As I use Ayanda arrays with a plastic pad, I can't really rely on metal plate heating and accuracy of cannula response becomes critical.

Many thanks for any info on that!

Hi Maksym,

the wire is supposed to create a turbulent flow. If you remove it you will end up with a laminar flow and unequal heating / temperature distribution.
I agree cleaning is easier and you reach higher flowrates but you will get an offset in the temperature. So if you remove the wire please carefully check if the perfusate temperature...

Thomas