Patent DE-102010045452-A1 (DE)
Title: Dosing device e.g. pipette device for aspirating and dispensing dosing fluids e.g. water and/or alcohol, comprises a dosing chamber, and a working chamber containing working fluid, which is displaceable in the working chamber
Inventor: KIRSTE VINZENZ
IPC: B01L3/02
Filed: 2010-09-15
Abstract: The dosing device (10) comprises a dosing chamber (18), a working chamber (16) containing working fluid such as ferrofluid, which is displaceable in the working chamber by a pressure impingement device such as a piston, and a housing. The dosing chamber and the working chamber are separated from each other by an elastic membrane, which is deformable by the pressure impingement device under the action of displaceable working fluid so that the available volume of dosing fluid in the metering chamber is variable to receive or discharge the dosing fluid by a dosing orifice (22). The dosing device (10) comprises a dosing chamber (18), a working chamber (16) containing working fluid such as ferrofluid, which is displaceable in the working chamber by a pressure impingement device such as a piston, and a housing. The dosing chamber and the working chamber are separated from each other by an elastic membrane, which is deformable by the pressure impingement device under the action of displaceable working fluid so that the available volume of dosing fluid in the metering chamber is variable to receive or discharge the dosing fluid by a dosing orifice (22) of a respective membrane facing into the dosing chamber. The membrane: in a central membrane region exhibits a protrusion (28) directed towards the dosing chamber; and in a rest position exhibits a deforming portion turned-out in the direction of working chamber. The deformation portion is formed such that: it is deformed with increasing pressure in the working chamber and inverted in the direction of the dosing chamber to alter the available volume of the fluid in the dosing chamber; and the membrane or membranes has or have a cross-sectionally wavelike profile with wave crests in the rest position of the working chamber. The protrusion directed towards the dosing chamber is arranged between the wave crests based on the cross-sectional profile of the membrane. The protrusion of the respective membrane is designed such that it has an outer contour contacting the dosing fluid, where an inner contour of the dosing chamber in the region of the dosing orifice is present in segments. The protrusion is formed like a truncated cone, which tapers from the membrane towards the dosing orifice. The working chamber is associated with a first membrane, and the dosing chamber is associated with a second membrane, where the first and second membranes partially lie against one another in the operational state of the dosing device. The two membranes are deformable under the action of the first membrane in contact with the working fluid upon actuation of an actuating element. The protrusion is provided on the second membrane. The first and/or the second membrane: is brought on an other side of an other membrane in a plant; and comprises a surface structure and/or coating, which is formed such that the two membranes fit together more detachably. A dosing chamber comprehensive dispensing tip is detachably connected or connectable with the working chamber comprehensive housing. The first membrane is connected with the housing of the dosing device, and/or a sheath is connected with the working chamber. The second membrane is connected with the dispensing tip, and the dosing device is releasably attached with the dispensing tip on the housing. The dispensing tip and the associated second membrane are: formed as a disposable article; and removable by the housing of the dosing device and the first membrane after use. The first membrane is made of a material having a lasting resistance to the fluid such as water existing in the working chamber. The second membrane is made of a material having a lasting resistance to the dosing fluid in the dosing chamber. The actuating element comprises a magnetizable or magnetized piston, by which an outer magnetic field is movable for displacing the working fluid and a desired amount of the dosing fluid into the dosing chamber for aspirating and dispensing the dosing fluids.