Multichannel Systems USB-MEA32-STIM4 Manual - Manual (Page 27)

USB-MEA32-STIM4-System
21
4.4.3 Pressure Control in the Suction Port
Pressure Control via CVP
The pressure control unit CVP (controlled vacuum pump) is a vacuum pump with a pressure sensor
and a waste bottle. A sensor measures the pressure in the compartment attached to the waste
bottle, and can regulate the suction to maintain a constant negative pressure. With this unit,
it is possible to precisely control the suction applied to the slice and to keep the negative pressure
stable during the whole recording period. The accuracy of the pressure control is 0.1 mbar,
the maximum negative pressure is 200 mbar below atmospheric pressure. A negative pressure of
10 to 30 mbar is enough to keep a slice in place on the electrodes. Please read CVP manual for
setting up the vacuum pump. In case of 50 Hz noise, include a metal part in the tubing to the
CVP and ground it to one of the systems ground connectors. It is also recommended to use a valve
between the CVP and the system.
Pressure Control via Syringe
Suction can be applied manually with a syringe.
Connect a 1 ml syringe to the tube. After mounting the slice, gently suck in about 20 to 50 μl with
the syringe. It is better not to start with the syringe at position 0 ml, better have 100 to 200 μl of
air already in. Do not apply more suction, or the slice will be sucked into the holes. Most likely
the negative pressure will dissipate over time, but usually the adhesion of the slice to the pMEA
surface is good enough by then to keep it in place anyway.