Pipetting method and pipetting device

A pipetting device for a liquid driven by a working medium, the pipetting device comprising

• at least one pipette connector (13) adapted to releasably attach a pipette at a pipette side of the pipette connector and having an opening (17) towards said pipette side,
• at least one of a positive pressure source (11′) and of a negative pressure source (11″) with respect to a reference pressure (20),
• a flow connection (12) between said opening (17) of the at least one pipette connector and said at least one pressure source,
• a flow restriction (40) in a form of a capillary or a micro-channel, being arranged in the flow connection between said opening (17) of the pipette connector (13) and said pressure source (11, 11′, 11″), separating the flow connection into an upstream portion (41) and a downstream portion (42) with respect to the flow restriction,
• a controllable discharge valve arrangement (14) configured to discharge a pressure in a working medium in said flow connection to the reference pressure (20),
• a time controller (15) operationally connected to said controllable discharge valve arrangement, and wherein the time controller comprises a pulse generator the output thereof being operationally connected to a control input of said discharge valve arrangement.

A pipetting device for a liquid driven by a working medium, the pipetting device comprising

• at least one pipette connector (13) adapted to releasably attach a pipette at a pipette side of the pipette connector and having an opening (17) towards said pipette side,
• at least one of a positive pressure source (11′) and of a negative pressure source (11″),
• a flow connection (12) between said opening (17) of the at least one pipette connector and said at least one pressure source,
• a flow restriction (40) in a form of a capillary or a micro-channel, being arranged in the flow connection between said opening (17) of the pipette connector (13) and said pressure source (11, 11′, 11″), separating the flow connection into an upstream portion (41) and a downstream portion (42) with respect to the flow restriction,
• a controllable discharge valve arrangement (14) configured to discharge a pressure in a working medium in said flow connection to a reference pressure (20),
• a time controller (15) operationally connected to said controllable discharge valve arrangement, and
• wherein a first controllable valve (51) is operationally interconnected between said positive pressure source and said pipette connector and a second controllable valve (52) is operationally interconnected between said negative pressure source and said pipette connector.

A pipetting device for a liquid driven by a working medium, the pipetting device comprising:

• at least one pipette connector (13) adapted to releasably attach a pipette at a pipette side of the pipette connector and having an opening (17) towards said pipette side,
• at least one positive and/or negative pressure source (11, 11′, 11″),
• a flow connection (12) between said opening (17) of the at least one pipette connector and said at least one pressure source,
• a flow restriction (40) in a form of a capillary or a micro-channel, being arranged in the flow connection between said opening (17) of the pipette connector (13) and said pressure source (11, 11′, 11″), separating the flow connection into an upstream portion (41) and a downstream portion (42) with respect to the flow restriction,
• a controllable discharge valve arrangement (14) configured to discharge a pressure in a working medium in said flow connection to a reference pressure (20), wherein the reference pressure (20) is ambient pressure, and
• a time controller (15) operationally connected to said controllable discharge valve arrangement, and wherein the controllable discharge valve arrangement (14) is configured to discharge the pressure through an opening different from the opening (17) of the pipette connector (13) or different from a pipette attached to the pipette connector (13).