My STAR has recently been failing to fully eject pipette tips once every ~500 tip pickups. The problem is not localized to any channels, and there’s no residue on the channels that they might be sticking to. I’ve heard others may have had this issue and that it could be related to static electricity clinging. We run our robots in a pretty dry environment so static cling would likely be worse in our case.
The tips are clear 1000uL filtered and non-filtered. I plan to update with lot #s when I can. I’ve attached a video that captures the behavior we’ve seen quite consistently.
I was wondering if anyone else has seen similar behavior on their Hamiltons (specifically CO-RE IIs) or any other robot for that matter and if the cause is likely to be static.
Sorry to hear about the issue. Ejecting back to a tip wafer doesn’t give you the added benefit of the “roll-off” behavior seen on eject on the tip eject tray to waste. You could try implementing a firmware command PXAA ts1 to add more up and down z movement on the eject which may help mitigate the tip cling. You can send the command at the beginning before the eject step and then disable it at the end and On Abort (use ts0).
Please provide the tip lot information when you can and send me a recent run trace so I have the system SN, software, and firmware versions (you can DM me with that info). I can follow up internally once I have more information!
I should add that you should put a move to sequence prior to initially sending the command as it actually does a tip shake wherever the channels are when you initially execute the command. Just to be on the safe side. When you later use the standard tip eject command it will do this additional tip shake.
In other words, the move command only needs to be set right before the first use of the firmware command.
Make sure the carriers are wiped down and cleaned on a regular basis. Dust a debris can isolate the carrier from the ground plane of the machine allowing a static charge to build up and cause these issues.
Bring the humidity in your lab up. The minimum specification from Hamilton for these units is 30% humidity. Operating below that can cause static issues as well as premature o-ring failures/cracking.
Get a small ionizer to blow over the deck. They sell a few models on Amazon.
If your system has the spill protection kit installed have your tech inspect the underside of the deck during the next pm. I have seen a number of these kits installed improperly where the green tape on the underside of the deck is in the area where the deck “should” be contacting the steel frame. This can also cause isolation and static buildup on the deck plane.
I second this. It doesn’t matter which vendor you have, everyone should monitor temp/humidity and install a small ionizer as an insurance policy if possible.
I’ve used this brand in the past ( link 1 & link 2 ) and was well worth the money.
Yes, from your video, certainly looks like static to me. We’ve seen this happen with bravo tips, lynx tips; first time I’ve seen with Hamilton tips, but we use the black ones. Exhibits the same kind of wobbliness though. Ionizer and temp/humidity monitoring would be good ideas.
Given the way it was floating there I still think it’s static related.
This could point to some of the other issues I mentioned above.
If there are isolated potential planes in the system, this could certainly contribute to the effect.
Are you using a BVS or CVS? Had any spills in the rear near the carrier stops?
On deck vacuum systems. Notorious for leaking fluids onto the decks which can contribute to grounding issues.
I only ask because they tend to require additional cleanup during PMs and maintenance.
You’d know it if you had one I think.
