Pipetting apparatus and methods

An automated pipetting system comprising:

• a pipettor including:
• a pipetting channel;
• a first plunger mechanism operable to change a pressure in the pipetting channel to aspirate or dispense a liquid;
• and
• a second plunger mechanism operable to change the pressure in the pipetting channel to aspirate or dispense the liquid;
• wherein:
• the first plunger mechanism includes a first chamber and a first plunger;
• the first plunger mechanism is operable to move the first plunger through the first chamber to change the pressure in the pipetting channel;
• the second plunger mechanism includes a second chamber and a second plunger;
• the second plunger mechanism is operable to move the second plunger through the second chamber to change the pressure in the pipetting channel;
• the first and second plunger mechanisms are operable to move the first and second plungers independently of one another to change the pressure in the pipetting channel;
• and
• the pipettor includes:
• a port to atmosphere;
• a valve fluidly connected to each of the second chamber and the port;
• and
• a controller configured to operate the valve to selectively control fluid communication between the second chamber and the port to selectively expel air displaced from the second chamber by the second plunger to atmosphere through the port.

An automated pipetting system comprising:

• a pipettor including:
• a pipetting channel;
• a first plunger mechanism including a first chamber, a first plunger, and a first plunger actuator configured to move the first plunger through the first chamber to change a pressure in the pipetting channel to aspirate or dispense a liquid;
• and
• a second plunger mechanism including a second chamber, a second plunger, and a second plunger actuator configured to move the second plunger through the second chamber to change the pressure in the pipetting channel to aspirate or dispense the liquid;
• and
• a controller configured to automatically control the first plunger mechanism and the second plunger mechanism;
• wherein:
• the first and second plunger mechanisms are operable independently of one another to change the pressure in the pipetting channel;
• and
• the controller is configured to aspirate a liquid sample volume by:
• automatically controlling the first plunger actuator to move the first plunger through the first chamber to aspirate a first portion of the liquid sample volume;
• and also
• automatically controlling the second plunger actuator to move the second plunger through the second chamber to aspirate a second portion of the liquid sample volume.

A method for operating an automated pipetting system, the method comprising:

• performing, by at least one control circuit, operations comprising:
• operating a first plunger mechanism of a pipettor of the automated pipetting system to move a first plunger of the first plunger mechanism through a first chamber of the first plunger mechanism to displace or replace an air volume in the first chamber and thereby change a pressure in a pipetting channel of the pipettor to aspirate or dispense a liquid;
• and
• operating a second plunger mechanism of the pipettor to move a second plunger of the second plunger mechanism through a second chamber of the second plunger mechanism to displace or replace an air volume in the second chamber and thereby change the pressure in the pipetting channel to aspirate or dispense the liquid;
• and
• operating a valve fluidly connected to each of the second chamber and the pipetting channel to selectively control fluid communication between the second chamber and the pipetting channel;
• wherein the first and second plunger mechanisms are operable to move the first and second plungers independently of one another to change the pressure in the pipetting channel.