Abstract: The present invention pertains to a method for detecting a fluid surface, comprising the following steps: providing at least one probe having an electric capacitance with respect to its surroundings; moving the probe into or out of a fluid; charging the probe by applying a periodic first electric signal to the probe for activating the probe; applying a periodic third electric signal to one or more electrically conductive regions different from the probe simultaneously with applying the first electric signal to the probe, wherein the third electric signal corresponds to the first electric signal or an amplified/damped first electric signal; at least partially discharging the probe so as to obtain a discharging current; detecting a second electric signal based on the discharging current; analyzing the second electric signal or a signal derived from the second electric signal with respect to the capacitance of the probe; identifying the fluid surface of the fluid based on a change of the capacitance of the probe

Abstract: A method and an automated system for discriminating bulk liquid from foam and/or residuals of the bulk liquid of a sample contained in a sample vessel are presented. A probe having an electric capacitance is provided and moved into the sample. Consecutive steps of charging and at least partially discharging the probe to generate a discharging current is repeatedly performed. A quantity indicative of the discharging current for the consecutive steps of charging and at least partially discharging the probe is measured. The quantity is analyzed to determine an electric resistance (Rmess) of the sample via the probe. The bulk liquid is discriminated from the foam and/or the residuals of the bulk liquid based on a change of the electric resistance (Rmess) of the sample occurring when the probe contacts the bulk liquid.

Abstract: A sample preparation dosing unit for liquid dosing is provided comprising an inlet port and an outlet port fluidically coupling the sample preparation dosing unit to a supply and target, respectively; a pump, fluidically arranged between the inlet port and the outlet port; an outlet flow restrictor with an outlet flow resistance, fluidically arranged between a pump outlet and outlet port; and a control arrangement with a branch, a control valve, and a control flow restrictor with a control flow resistance. The branch divides the flow at the pump outlet into an outlet flow through the outlet flow restrictor and into a control flow through the control flow restrictor. The control flow downstream of the control flow restrictor is fed, depending on the state of the control valve, either into the outlet port thereby merging with the outlet flow downstream of the outlet flow restrictor, or into a bypass conduit.

Abstract: The present invention pertains to a method for detecting a fluid surface, comprising the following steps: providing at least one probe having an electric capacitance with respect to its surroundings; moving the probe into or out of a fluid; charging the probe by applying a periodic first electric signal to the probe for activating the probe; applying a periodic third electric signal to one or more electrically conductive regions different from the probe simultaneously with applying the first electric signal to the probe, wherein the third electric signal corresponds to the first electric signal or an amplified/damped first electric signal; at least partially discharging the probe so as to obtain a discharging current; detecting a second electric signal based on the discharging current; analyzing the second electric signal or a signal derived from the second electric signal with respect to the capacitance of the probe; identifying the fluid surface of the fluid based on a change of the capacitance of the probe

Abstract: A system and a method for the automated pipetting of fluids are disclosed as well as a method for calibrating the system. A channel pump having at least one tip-sided port connected to a pipetting tip by a tip-sided pump conduit for generating a positive or negative pressure in the pipetting tip, and at least one reservoir-sided port connected to a system fluid reservoir by a reservoir-sided pump conduit is provided. The channel pump when operated at a nominal flow rate exhibits a fluid backflow caused by a pressure difference in the tip- and reservoir-sided pump conduits which results in an effective flow rate compared to the nominal flow rate. Such a pressure difference can be used to determine an extended pipetting period which extends a pipetting period of the channel pump operating at the nominal flow rate, and to calibrate the system.

Abstract: A system and a method for the automated pipetting of fluids are disclosed as well as a method for calibrating the system. A channel pump having at least one tip-sided port connected to a pipetting tip by a tip-sided pump conduit for generating a positive or negative pressure in the pipetting tip, and at least one reservoir-sided port connected to a system fluid reservoir by a reservoir-sided pump conduit is provided. The channel pump when operated at a nominal flow rate exhibits a fluid backflow caused by a pressure difference in the tip- and reservoir-sided pump conduits which results in an effective flow rate compared to the nominal flow rate. Such a pressure difference can be used to determine an extended pipetting period which extends a pipetting period of the channel pump operating at the nominal flow rate, and to calibrate the system.

Abstract: A sample preparation dosing unit for liquid dosing is provided comprising an inlet port and an outlet port fluidically coupling the sample preparation dosing unit to a supply and target, respectively; a pump, fluidically arranged between the inlet port and the outlet port; an outlet flow restrictor with an outlet flow resistance, fluidically arranged between a pump outlet and outlet port; and a control arrangement with a branch, a control valve, and a control flow restrictor with a control flow resistance. The branch divides the flow at the pump outlet into an outlet flow through the outlet flow restrictor and into a control flow through the control flow restrictor. The control flow downstream of the control flow restrictor is fed, depending on the state of the control valve, either into the outlet port thereby merging with the outlet flow downstream of the outlet flow restrictor, or into a bypass conduit.