The OT-2’s default parameters have been optimized to work with aqueous reagents. Because of this, viscous liquids will require some adjustment of these parameters to improve liquid handling abilities. From internal testing, we know that the OT-2 with GEN2 pipettes can handle viscous liquids of varied viscosity with accuracy comparable to water handling capacity of OT-2 along with high precision. Here are some tips on how to handle these liquids to have a successful protocol run.
The first step is to aspirate/ dispense slowly so you have a clean aspiration/ dispensing cycle.
Dead volume is generated if the excess liquid inside the tip is not removed after blow out.
The lower flow rate allows all the liquid to be removed compared to higher flow rate where the liquid dispenses from the center but excess liquid sticks to the wall of the tip.
Normally after completing a dispensing step, using a slower flow rate is recommended for the blowout function.
However, if the blow out volume is too low or too high for the liquid dispensing:
An air gap can be implemented before aspirating ( currently only in the Python API) combined with a slower dispense rate
The trade-off is that less liquid can be aspirated to prevent exceeding the maximum volume limits of the pipette.
This is not recommended for GEN2 P20S pipettes
Something that is also recommended is a slower withdrawal speed after aspiration and dispensing.
This prevents sticking of droplets on the tip and spilling of reagents in the labware.
Additionally, it is recommended that before aspirating or dispensing that you use move_to () to move the pipette tip close to the bottom of the labware at 10mm/s
After aspirating / dispensing, you should use move_to() to move the pipette tip at 1-5mm/s to the top of the labware.
Recommended parameters for handling viscous liquids. Keep in mind that these are guidelines, so you may have to change parameters a bit to fit your needs:
If you would like to learn more about the our viscous liquid testing, you can read about it here: https://opentrons-landing-img.s3.amazonaws.com/application+notes/Viscous+Liquids+App+Note.pdf
If you have any questions or need any assistance, please contact Opentrons support at firstname.lastname@example.org.