Patent ID: 7770757

Claim:
Microdosing device for a liquid medium comprising a dosing compartment and an electrically or electronically activatable vibration unit which can cause at least one contact area of the dosing compartment to vibrate for the delivery of a volume of medium and a medium reservoir which is connected to the dosing compartment by means of a first flow channel, wherein a manually operable mechanical piston pump for conveying medium to the dosing compartment is assigned to said first flow channel, wherein said first flow channel comprises a mechanical nonreturn valve between said piston pump and the dosing compartment, said nonreturn valve inhibiting back flow of contaminated liquid medium from the dosing compartment to the piston pump, and wherein a second flow channel branches off from said first flow channel between the nonreturn valve and the dosing compartment to the medium reservoir, said second flow channel having a filter device.