We are starting to use the Grenova washer to wash our Hamilton tips. And while the washing seems to work, we end up having a bit of water volume in the tip.
Is there a way with Venus (classical or firmware commands) to aspirate air before tip pickup and do a blowout once the tips are picked up to removed any liquid left in it ?
The labware properties (screenshot) are in the Programmers Manual. As for the knowledge of how this works, I am not sure if this info is documented anywhere particular but I asked Hamilton a similar question like 7 years ago when I was battling residual volume in tips from tip reuse.
Would love for a Hamilton rep to correct me if I am wrong on how this works
Hello,
Have you managed to determine how to select the pre-aspiration air volume?
I encountered the same issue and attempted to resolve it by enabling the labware properties mentioned. It pre-aspirates an undetermined volume of air before attaching the tip, yet the following problems remain:
I cannot find a way to select the pre-aspiration volume.
I am unable to initiate a dispense volume without first performing an aspirate step.
The pre-aspirated air is not being dispensed.
(I also tried aspirating a zero volume with the blow-out tip dispense mode.)
Personally, Iâm not using washer, but I need to pre-aspirate air for another reason. Specifically: Pre-aspirate air (choosing the volume), Tip pick up , dispense air, tip eject.
Any suggestion would be appreciated
This might be something youâd need firmware commands for - Iâm not sure if those exist where you could do something likeâŚ
Aspirate v vol @ z height with n tips
Get tips
Dispense v vol @ z height with n tips
Drop tips
You can trick the system to aspirate sans tip pickup by using error handling and empty tip wafers, but Iâm not confident that the piston position would be preserved after dropping those fake tips to pick up real tips. Most likely the piston is zeroed after each tip eject.
Maybe something like this? If it works?
Get tips @ empty position
Error handling: ignore non-pickup
Aspirate v vol anywhere safe
Eject tips
Get real tips
Dispense v volume @ waste or something
You can use âMlStarIsCoreHeadSpecialTipPickupâ property of the tip rack to pre-aspirate air that is then blown out AFTER picking up the tips. Setting âMlStarIsCoreHeadSpecialTipPickupâ = 1 will activate this property.
You can use âMlStarIsCoreHeadSpecialTipPickupâ = 2 to pre-aspirate and NOT blow out immediately (so that you can blowout into a waste or something with a dispense command) but I do not recommend using this because there are serious bugs associated with this property. Using â1â is safe though and does not require bug handling.
This property would ideally meet my requirements: to pre-aspirate without immediate blowout (possibly blowing out into waste or another position via a dispense command). Additionally, after picking up the tip, I want to avoid aspirating extra air, but only blow out the air that was pre-aspirated.
The challenges I encountered with this feature include:
Thereâs no option to select a pre-air volume (although this may not be a concern for me).
Iâm compelled to perform a dummy aspiration (volume 0) AFTER picking up the tip, but I observed that the pre-aspirated air doesnât blow out when using the dispense command.
Could you suggest a specific setting or liquid class that would allow for the blowout of pre-aspirated air?
I really appreciate your help
If I understand your use case, you can use âMlStarIsCoreHeadSpecialTipPickupâ = 2 to achieve your goal. This property will allow you to:
Aspirate air
Pickup a tip rack with the assigned property
Follow the pickup with a âBlowoutâ dispense step.
To circumvent the bug associated with this property you will need to follow these steps.
Use the âValueforkeysetforpropertiesoflabwareâ step within the âLabwrAccessâ library to change the âMlStarIsCoreHeadSpecialTipPickupâ to 2 for the tip rack of interest.
Perform your pickup and blowout.,
Build in a property âresetâ at the end of your method AND on abort. This reset involves again using âValueforkeysetforpropertiesoflabwareâ to set the âMlStarIsCoreHeadSpecialTipPickupâ* to 1, performing a fake tip pickup/eject, then using the library to set âMlStarIsCoreHeadSpecialTipPickupâ** to 0, then performing yet another fake tip pickup/blow.
You must go from 2 â 1 â 0 to achieve a proper property reset. If you do know perform the reset as outlined and complete/abort your method, ALL pickups will inherit a property of 2. This is not catastrophic but you will probably get âplunger out of bounds errorsâ and need to powercycle to reset the firmware.