The invention relates to a method for picking up cell material from the surface of a culture medium in a culture dish.
Such a method is known from JP-A-62273429. This known method is related to obtaining a constant needling depth by using a transplanting needle as an electrode and detecting contact between the transplanting needle and a culture medium by an electric signal. An electrode is positioned over the culture medium and then the transplanting needle is lowered to the culture medium. A power supply and a variable resistor are connected to the electrode and the transplanting needle by a lead wire. Since the culture medium has high moisture content, the presence or absence of conduction can be detected by a detector and a detection threshold can be changed by adjusting the variable resistor. A problem that might arise when using this known method is that although a constant needling depth can be obtained it sometimes appears that the transplanting needle has picked up a mixture of cell material and of culture medium below the cell material. In addition the power supply connected to the electrode and the transfer needle produces a current through the culture medium that can be detrimental for the cell material on the culture medium. In addition when changing towards a different culture dish the electrode has to be replaced or thoroughly cleaned to prevent cross-contamination.