Patent ID: 8021627

Claim:
A pipetting device, comprising: a displacement chamber ( 30 ); a flexible membrane ( 20 ) delimiting the displacement chamber ( 30 ); a driving equipment ( 13 ) for deforming the membrane ( 20 ); a coupling equipment ( 15 ) between the driving equipment ( 13 ) and the membrane for coupling the driving equipment ( 13 ) with the membrane ( 20 ); an equipment ( 6 ) for detachably holding a pipette tip, and a connection channel ( 7 ) between the displacement chamber ( 30 ) and the equipment ( 6 ) for detachably holding the pipette tip; further characterized in an aperture equipment ( 21 ), for adjusting the size of at least one aperture opening ( 28 , 29 ), the aperture equipment ( 21 ) covering the edge region of the membrane ( 20 ) with the at least one adjustable aperture opening ( 28 , 29 ) straight through which the central region of the membrane ( 10 ) is deformable.