Tip Touch on Aspirate for Thick Lysate?

Hamilton (Venus)
1

Hey y’all,

Our team is trying to optimize the liquid handling for a particularly difficult lysate with a 384 CO-RE head. So far we have got it relatively consistent, but we are beginning to explore less conventional approaches to handle some edge cases.

We noticed that occasionally, droplets will form on the outside of the tip on the aspirate step, which causes extra volume to be transferred to the destination plate. To try to account for this, ideally we would want to raise the head by a few millimeters after the aspiration, perform a tip touch in the source plate, then raise the head at a high speed to its regular safe movement height (this is done to break strings formed by the lysate).

We are not aware of a way to achieve this with the stock commands and libraries available to us. Does a library exist that could help us perform such an operation? Does anyone have other suggestions on how we could mitigate this issue? Please advise. Thanks!

2

@cponsi

This is the first thing I would try for this particular scenario:

  1. Aspirate as current, using the lysate liquid class. The MPH will retreat to traverse after, breaking the strings described.
  2. Using a separate dispense step, use a side tough dispense of 0uL to the source plate, using a different liquid class that has no airgaps (no additional plunger movement). You will of course want to optimize the side touch parameters to an acceptable height of the well, which is defined in the container definition of the rack.
  3. Dispense to target using the lysate liquid class.

This approach would allow use of default VENUS instrument steps, which is always ideal.

Hope this resolves the issue.

-Nick

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