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Opentrons / opentrons

Software for writing protocols and running them on the Opentrons Flex and Opentrons OT-2
https://opentrons.com
Apache License 2.0
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bug: Pipette's performing plunger unsticking within wells #9687

Open Matt-Zwimpfer opened 2 years ago

Matt-Zwimpfer commented 2 years ago

Overview

Some users have noticed that pipettes (notably the GEN2 P300 multichannel due to its particular noise) are going through the plunger unsticking procedure while in labware wells. This can cause vibration and reagent contamination. At the moment, it doesn't appear that there is anything in our API software which specifically prevents unsticking while tips are in a well.

Steps to reproduce

Exact procedure to reproduce this may be difficult, as this can happen randomly. It is most noticeable if a GEN2 P300 multichannel is used and in the protocol the noise associated with unsticking the plungers occurs happens while the tips are in the well.

Current behavior

Pipettes will perform unsticking behavior at set times and before a plunger motion if the plunger simply has been not moved for a certain period of time.

Expected behavior

Would be good to have some preventative condition where unsticking will not occur with tips within a well/in a safe (Z) position on the robot.

sfoster1 commented 2 years ago

I think this one needs to be solved in PE/protocol execution in general. The hardware controller and below have no idea about when the pipette is or isn't in a well. Having PE do a little fake aspirate or dispense before well entry, or issue a home-plunger after long pauses, may be all we can do.