| CPC B01L 3/0237 (2013.01) [B01L 3/0227 (2013.01); B01L 2300/0663 (2013.01); B01L 2400/0478 (2013.01)] | 20 Claims |
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1. A pipetting device for pipetting, that is, for aspiration and/or for dispensing, of a dosing liquid under the mediation of a working gas, where the pipetting device comprises:
a pipetting duct extending along a duct axis,
a pipetting piston movable in the pipetting duct along the duct axis,
an accommodating space for accommodating dosing liquid, which extends in the pipetting duct along the duct axis from a pipetting aperture at one end up to a dosing-side piston surface of the pipetting piston facing towards the pipetting aperture at the other end, where working gas is accommodated in the pipetting duct immediately adjacent to the dosing-side piston surface, where a working gas reference volume is defined by the volume of working gas which is situated in the accommodating space under a working gas reference pressure,
a driving device coupled in a force-transmitting manner with the pipetting piston, configured to displace the pipetting piston along the duct axis,
a position acquisition device which acquires a position of the pipetting piston along the duct axis and outputs a position acquisition signal representing the acquired position,
a pressure acquisition device which acquires a pressure of the working gas in the pipetting duct and outputs a pressure acquisition signal representing the acquired pressure, and
a control device,
where the control device is configured to actuate the driving device in accordance with
the pressure acquisition signal,
the working gas reference pressures, and
a defined target dosing liquid volume to be pipetted,
taking into account a pressure change-induced change in the working gas reference volume effected by the piston movement,
where the control device is further configured to perform the piston movement required for pipetting the target dosing liquid volume in several consecutive movement steps,
wherein the pipetting duct exhibits a first working range whose known base temperature lies in a lower base temperature range and a second working range whose known working temperature lies in a working temperature range higher than the base temperature range, where the control device is configured, after a first pipetting piston movement step for a subsequent pipetting piston movement step,
to establish a first correction variable which represents a pressure change-induced volume change in a part, located in the first working range, of the of the working gas volume enclosed in the pipetting duct, on the basis of the position acquisition signal, of the pressure acquisition signal, and of the working gas reference pressure, and
to establish a second correction variable which represents a both pressure change-induced and temperature change-induced volume change in a part, located in the second working range, of the working gas volume enclosed in the pipetting duct, on the basis of the position acquisition signal, of the pressure acquisition signal, of the working gas reference pressure, of the known working temperature, and of the known base temperature,
and to establish a target step movement volume of the pipetting piston on the basis of
a step reference volume assigned to the subsequent pipetting piston movement step,
a previous displacement volume of the dosing-side piston surface of the pipetting piston in the current pipetting procedure,
the first correction variable, and
the second correction variable and to actuate the driving device in accordance with the established target step movement volume.
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