Dear lab automation community,
I am looking for you help on a problem I have contacted the Tecan support already. Unfortunately, they were not able to help me.
If I am moving the pipetting arms of our Fluent to the same physical height (related to the end of the pipet tip), the move tool shows a different z-value. Vice versa, if I am moving the arms to the same z-height in the move tool they differ aprox. 1.5 mm in height (related to the end of the pipet tip). If I would teach a plate with one arm, the other could crash into the plate. Both arms have been calibrated twice by a Tecan technician and passed. The issue still exists. I really want to solve the issue to prevent that someone accidentally teaches a plate to the wrong arm. In this case, all liquid classes previously defined for this plate would not work anymore. I even do not know to which arms the plates have been teached before.
Ideas how to solve the problem from my side:
adjust labware for pipet tips (I already checked that)
adjust reference point for calibration of arms (I am not allowed to do this)
Of course, I know that the z-positions in the labware definition of the plate are just points of reference. You can define the exact position the arm moves to in the liquid class. However, this work around would not mitigate the risk I mentioned. You can leave out this answer.
Thanks a lot for helping me.
Kinds regards,
Dominik
An annoying workaround could be in your scripts before using an arm, you do
SetVariable:
SetAttribute(“<any_random_labware>”,“Adjustable_Height”,“<your_offset_value_here_depending_on_the_pipette_being_used>”)
Then in the liquid class, you can set variable: GetAttribute() and retrieve that number, and assign it to your z_offset value in your liquid class (or just add it to your z_value, as in: if you go to z_Max, just do z_Max + offset_value_from_labware
The reason I say assign it to a random labware is because liquid classes cannot access variables from the script/run, so you have to do this weird thing to access them. This is essentially just a switch that turns on or off depending on the arm you’re using (if it is indeed always a 1.5 mm difference).
Dear Shinedalgarno,
thanks for your suggestion. The expert line of Tecan suggested something similar.
However, this does not solve our problems in regards of teaching and cLLD. I prefer finding the reason for the offset.
Regards,
Dominik
Wow. Really great feedback in no time. Thanks a lot.
For the details:
We were testing with 350 uL DiTis on the FCA and 200 uL DiTis on the MCA (with EVA adapter). All DiTis we use are Tecan provided.
Some difference in the 100-200 um could be seen within the different tips (FCA/MCA)
There were problems in the past in the pickup of FCA DiTis. They are a little tilted sometimes. However, I don’t think this would cause such a big offset. Tecan was already investigating this issue in the past. We got new DiTi coni and different batches of tips were tested.
We are not using custom labware or nests as far as I know. The set up was done by a Tecan Application Specialist 2 years ago.
The technician from Tecan was using fixed tips/tools for the FCA and an adapter plate with reference pins for the MCA. The z-displacement they measured was 1.6 mm, which is really high according to their oppinion. It is difficult for me to judge wether the tools from them were fine. I assume so.
@Optimize: By the labware offset, which property do you mean? Should I measure the mounting offset? Or maybe it was adjusted in the past by someone. I could check against the standard settings.
in each DiTi labware definition (default, read-only), there is a custom attribute called “tip dimension”
i would consider creating a custom 350 uL tip type (so you can make adjustments), and adjusting the tip dimension height to overcome the 1.6 mm discrepancy in the displacement
it also sounds like this issue is > 2 years old - which version of FluentControl are you using?
does the same issue occur if you were to pickup 1 mL tips with the FCA ?
yeah that might be an idea. But you have to adjust every tip type. Normally, one would assume that the default tip types would work. We are also using 1 mL tips with the FCA, but I did not check with them. I will do so.
So far, I think, it was never a problem since one labware was just accessed by one arm. You can just teach it and that’s it.
We are using version 2.8. The device was installed 2020. I just joined the company. Before, most of my work was done by an application specialist from Tecan.
The attribute tip dimension is only reffering to the length of the tip. There is also mount offset, is that what you mean? Or is it a mix of both. The documentation of Fluent control is almost not existant. I could not find any information on this, yet.
i would request Tecan provide an update to latest FluentControl version
the tip labware has a couple of parameters - i would focus on “tip dimension” change to determine if adjusting by 1.6 mm alleviates the problem
another possible choice is to define labware with multiple “compartments” - this way, compartment 1 can have optimized X, Y & Z settings for FCA, compartment 2 can have optimized X, Y & Z settings for MCA (f the issues are arm based, the 2 x compartments would work; if the issue is across different tips, it’s more complicated)
for the record, the above are all “work arounds” - definitely push Tecan for a deeper dive into the issues as ~1.6 mm in a 96 well plate equates to a volume of ~50 uL
documentation is a definite deficiency - knowledge of FluentControl resides in people mostly - this forum is becoming a proven means of getting answers outside of the normal “helpdesk/expertline” channels
PLUS, you don’t have to wait 7-10 days for someone with 1-2 years experience to ask a follow up question - you can message actual users, who’ve worked through the nuances of the software, find people with > 10 years experience in FluentControl & get answers very quickly
i’ve started a training curriculum for “advanced fluentcontrol” training to showcase the various aspects of utilizing the multiple levels of functions made available in the software
This is a good opportunity to audit the setups you’re inheriting, verify that you’re using defaults where you can (although some people may argue to never use the defaults but that’s different) and also it will be worth upgrading to a newer version so you can re-import the default definitions of things.
When “teaching” definitely make sure that you do not have Zero G enabled once taught, you want to lock that arm up before transferring teachings. Also remember that labware and tip size matters, you will not get similar teachings if you’re dealing with a v shaped bottom and are using a slim tip and comparing that to a fatter tip that is also trying to reach the bottom.
In addition, I would maybe ask for a different FSE to come in and just re-perform their setups with a different reference deck segment and a different set of tools. Sometimes the tools aren’t properly tightened or have small variations which can have large impacts.
1.5mm is an insane difference and in my experience, rarely happened once we started to standardize the setup/reference tools.
Tecan did some internal research, but they say the hardware problem can not be solved. In addition, the same difference was recorded already during device setup 2020. I will try to escalate it now within Tecan. Let’s see if it helps.
Thanks a lot for all of your suggestions. I like the one with the pipet tip dimensions. So far, I basically only adjust for the alignment within the liquid classes and I started an overview which labware was taught on which arm. I will leave it like this until the route cause is solved.
Hi, Just come across this post. The issue is that Fluents are setup with the FCA and MCA the same z to support tip pickup and pre-taught labware. If you need to use fixed tips of different lengths or need fine tuning the heights, then these are normally pre-set in the factory for you but there is an in field work around.
I would contact Helpdesk@tecan.com again and request information about TeWiki ticket 6367 about “Fluent & FluentControl: How to set up a custom Fixed Tip”. This is something I cannot share on a public forum as it is internal information. This will need a FSE to also access to Setup and Service to lock in the different FCA settings.