Hi, I’m trying to optimize liquid class for pipetting very low volume (~5ul) pipetting on the Biomek i7 using the 96-head with BC50F tips. I get consistent results in testing with H2O but with media it’s been difficult.
I’ve tried adjusting several factors such as enabling pre-wet, slowing the asp/dispense speed to 3ul/s, asp/disp height, increase delay, etc. but for some reason on a PCR plate (narrow conical wells), the volume levels become inconsistent in each tip channel.
See this pic for example, but with full skirting all around.
Any suggestions on what I might be able to try before contacting service for hardware inspection?
Edit: To specify, it is not aspirating evenly inside the 96 channels from the above labware and there is no identifiable pattern on volume levels in each tip.
Is there a wicking effect within the tips? Additionally with those type of plates, I would not be surprised to see warping that could “pin” some tips while others are unblocked.
Besides that, one trick that has helped me with low volume on Biomek is to exit the liquid after pre-wet. The technique would essentially pre-wet as normal, then after dispensing the prewet volume simply raise the pipette tip to well top or some z height above liquid level, then resubmerge before pipetting. I’m not sure exactly why re-entering the liquid after prewet helps but I’m able to pipette down to 2µL accurately with this method. Oftentimes, you will need to double-touch at the target well to ensure the volume is delivered or otherwise dispense at z_liquid + 0 depending on how accurate your teaching is. The interface at the dest well can be stronger than the dispense pressure at this low of volume, meaning the volume won’t reliably dispense.
Otherwise, if there is excess well volume you can overaspirate, overdispense, then re-aspirate from the target well to leave the desired remainder in the target well. This will also be more accurate than transferring a low volume direct from source → target
