I’m experiencing an issue in with custom labware when during aspiration process. When I aspirate 10 uL (300 uL conductive tip) in my custom labware (96 well PCR plate) I get a “lost on Z drive error” when using cLLD and insufficient liquid error when using pLLD and the volume is lower than 50 uL.
I double checked all the dimensions (inumerous times), also done the “teach” procedure. I created a quick “move to” incrementing 1mm steps to the height to check are being “read” correctly and I had no problem with that.
I can’t find what my problem can be. Can anyone help me with that?
Difficult to say without having more information like the .rck and .ctr definition, the coordinates of the labware, what carrier module it’s on, and the details of the aspiration step. A step loss on Z-drive is usually from colliding with something while moving in Z. Is liquid following on? Do you have a submerge depth set?
This prevents the tip from moving all the way to the bottom of the plate which is likely why the cLLD is throwing a step loss error. Depending on how much is in the well, there may not be enough grounding to get a signal, and it is moving to z max looking for the liquid.
For the insufficient liquid level error, that means the channels do not have enough room to liquid follow and also have a submerge depth. If there is only 10uL or similar volume in the well and you have liquid following and or a 2 mm submerged depth you will get an insufficient liquid level error as the liquid level is roughly the distance of the submerge depth.
I would recommend using an aspiration mode of aspirate all in your aspirate step to minimize this error as it tells the firmware to not throw an insufficient liquid level error (it will still throw a liquid level error if no liquid is found). I would also suggest using a shallow submerge depth like 0.5-1 mm with no liquid following. Since this is a very small liquid amount, it isn’t necessary.
I agree with Brandon, there is not enough liquid to use cLLD, that is why the channel is moving until it hits the bottom of the well.
pLLD is more accurate here, as it is not affected by the volume. But there may be an issue that bubbles are created during the pLLD. So be careful with that.
Depending on your type of liquid, it may be advisable to increase the cLLD sensitivity and then separately define the aspiration position from the detected liquid level height. You can use the step return function for this.
Also, you can decrease the submerge depth. In these types of wells 1 mm is a lot already.
The insufficient liquid error stems from a bug in the volume calculation of Venus. I would therefore suggest that you calculate your volume separately and define ypour aspiration position so that it fits what you need to do.
Thanks a lot for your insights, Brandon! When I turned off the cLLD, pLLD and the liquid following, changed aspiration mode to “aspirate all” it worked!
Thanks for the insights, Florian! Right now I’m working with classic master mix buffers, but I’ll need to deal with a solution with colonies on it for colony picking (using EasyPick II) in the near future. I’ll soon try to increase cLLD sensitivy and change the aspiration position as you sugested. Right now I turned all the LLD off as suggested by Brandon and it’s working nicely
