Droplets on sidewall - Hamilton Vantage

[MikeMueller]

Hi Hamilton gurus and @EricSindelar_Hamilton,

I am working on a Hamilton Vantage running Venus on Vantage 4.6. The script is setup with multi-dispense and is using Jet Partial style liquid classes. We are seeing droplets on the sidewalls of the deepwell plate, at approximately the height it is set to dispense - currently dispensing water in testing. In the various wells, it is occurring seemingly randomly on different sides - sometimes the left sidewall, sometimes the top, in other cases the right.

I tried making some changes to dispense rates and some of the other liquid class settings. I am wondering if there may be a touchoff setting buried somewhere that I am missing. The script command in this script is one of the higher level commands that just takes in variables - the sequences, the liquid class, the height from the bottom, etc., so outside of the liquid class parameters and plate definitions, I’m looing for what other knobs to turn to try to dial this in.

Thank you,
Mike Mueller

[EricSindelar_Hamilton]

Hi Mike,

This thread shows how to enable/disable the side touch.

There is a section on best practices for multi-dispensing in the liquid handling reference guide. The guide also covers each liquid class setting.

For jet part dispenses, there is a parameter called the Stop Back Volume that is only enabled for this mode. This is a volume that is aspirated again immediately after the dispense. So it dispenses the aliquot and then aspirates this stop back volume quickly to prevent excess liquid from coming out. Its value would depend on the aliquot volume and liquid property but typically is set to 5-12µL range.

The recommended approach is to set this value so that there is no air gap at the end of the tip in between the multi-dispenses.

Proper stop back volume - no air gap at the end of the tips

Excessive stop back volume - too much of an air gap at the end of the tips

I hope this helps!