Abstract: Apparatus and methods for controlling the insertion of a membrane channel into a membrane are disclosed. In one arrangement a first bath holds a first liquid in contact with a first surface of a membrane. A second bath holds a second liquid in contact with a second surface of the membrane. The membrane separates the first and second liquids. A first electrode contacts the first liquid. A second electrode contacts the second liquid. A driving unit applies a potential difference across the membrane via the first and second electrodes to promote insertion of a membrane channel into the membrane from the first liquid or the second liquid. A membrane voltage reduction unit is connected in series with the membrane. The driving unit applies a driving voltage across the membrane voltage reduction unit and the membrane, the driving voltage providing the potential difference across the membrane.