In the “Pipetting” menu, you can set several options according to the needs of your application. These pipetting parameters are organized in four sections: Configuration, Advanced, Automation and Guidelines.
Under the “Advanced/Tip position” section in the “Pipetting” menu, you can set the position where the pipette tip should be immersed, suiting your application best while aspirating at the source. You can choose between “With respect to liquid” and “With respect to bottom”.
In some cases, you might be required to aspirate from the bottom of your labware, since the reagent you want to transfer collects on the bottom (settles), while in other cases following the liquid surface might be a better option.
Similarly, during the dispensing at the destination, you can choose between these options to set the height of the tip:
- With respect to liquid: With this option the robot will track the liquid height as it pipettes
- With respect to bottom: select this option only when the tip will not get submerged
- On-the-fly: should be enabled when the tip should remain on top of the destination labware without being in contact with the reagent. This option is recommended when you would like to avoid bubble formation when certain reagents are used and contamination (of the source) if the same tip is reused for several transfers. Beware that this height above the consumables may result in splatter effects of certain liquids with droplets or mist ending up outside the target destination, potentially causing contamination of samples in other labware.
Besides the tip position you may also choose to activate the “Tip touch-off” option. This means that the last small drop of reagent that is potentially still connected to the tip will be put into the destination labware by touching the wall of the labware, or the liquid surface of the reagent, such that due to the surface tension, the drop is released from the tip. Manual execution of the protocol allows for tip touch-off on the wall of the labware, tilting the pipette relative to the labware. Andrew+ can only move the pipette in the vertical direction and therefore, the tip touch-off is at the liquid surface instead. Therefore, the liquid level needs to be known very precisely. This option is especially interesting when very small quantities of reagent are transferred and helps to ensure the complete removal of the reagent present in the tip. When Andrew+ is used to execute the protocol, the tip-touch off is on the liquid surface, the robot is only able to move the pipette in the vertical direction and not change the angle with the vertical, thus it is not able to touch-off on the labware wall.