PH01 perfusion cannula

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PH01 perfusion cannula

Post  holly87 on Wed May 08, 2013 5:19 am

Hi,
I'm doing the very first experiments with your perfusion cannula PH01 + temperature controller + a syringe pump. I carefully read the PH01 manual, and I would like to ask you some questions, in order to exploit all the potentiality of this device and establish a correct perfusion setup.

1) I read that there is a titanium filament inside the cannula to create a turbolent flow and that it is not suggested to remove it. So, the culturing medium is in contact with metallic materials (i.e., titanium filament and stainless steel perfusion cannula). How can I face the problem of sterility and maybe metallic ions delivered from metals to the medium?
2) Is also the pt100 internal sensor in contact with the medium or it is in contact with the stainless steel tube where the medium flows? In the latter case, I don't understand how it can accurately measure the temperature of the liquid..maybe because the stainless steel cannula has a very low wall thickness? Embarassed
3) I read that one of the screws in the rear side must be connected to ground, so that the cannula tip is linked to ground by means of a capacitor. So, it is linked to ground for high frequency, right? Could you explain me why this is needed?
4) I read that air drifts near the cannula lower the temperature at the level of the cannula tip and so the cannula should be shielded from air drafts. How can I do that? It is ok if I simply cohibent the cannula tip with an insulating sheath?
5) I read that if I want to use a flow lower than 500 ul/min the device does not operate correctly. I guess that this is due to the fact that such low flow rate cause a cooling of the medium even at the level of the cannula tip.. Can't I face this problem by simply rising the setpoint temperature?

Thank you very much !

Best regards
Holly

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Re: PH01 perfusion cannula

Post  Frank MCS on Mon May 13, 2013 9:04 pm

Dear Holly,
the sensors measure the temperature of the cannula, which of course does not reflect 100% the temperature of the solution. To set up a slow perfusion with medium, I'd put a sterile filter between the PH01 and the culture, and run the perfusion with the desired speed at the desired place with the room temperature as constant as possible, and no AC blowing directly at the PH01. Then you measure the temperature inside the MEA dish with an external thermometer. This will probably give you a difference of maybe 1 between the actual temperature in the dish and the set temperature of the PH01. Adjust the set temperature till the actual temperature is what you want. As long as all parameters stay the same (flow speed and room temperature especially), this offset will be constant.

Best regards Frank MCS
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Re: PH01 perfusion cannula

Post  holly87 on Tue May 14, 2013 4:25 am

Dear Frank,
thank you very much for the suggestion!
I have only the doubt regarding the grounding of the PH01. I read that one of the screws in the rear side must be connected to ground, so that the cannula tip is linked to ground by means of a capacitor. Why this is needed? What happens if I can't do that?
Greetings
Holly

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Re: PH01 perfusion cannula

Post  Frank MCS on Tue May 14, 2013 7:42 pm

Dear Holly,
if you just perfuse without simultaneous recording, grounding is not necessary. If simultaneous recordings are planned, the perfusion will introduce huge 50Hz noise, as it acts as an antenna connected to the bath. You can also connect the cannula of the PH01 directly with a crocodile clamp to the system ground, it is not essential that xou use the screws.

Best regards Frank
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