cLLD vs. fixed height

Hamilton (Venus)
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Hi all, I was wondering what your experience has been with volumes under 10 uL. Have you seen better results using cLLD or fixed height for aspirate, dispense, and mixing? Thank you!

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For aspirate:
Both cLLD and fixed height work well. For example, when pipetting less than 10ul out of a 1.5ml tube I usually just pipette near the bottom. When pipetting out of a 200ul well I more prefer cLLD. You have to test both in your assay to determine what works best CONSISTENTLY. The low volume pipette steps can be finicky.
Also don’t use the 10ul tips, I don’t know why but they aren’t as accurate as the 50ul tips at low volumes and the cost is higher.

For dispense:
If it’s an empty well I touch off the bottom then jet dispense at 0.5mm with liquid following on. I also changed the liquid class quite a lot to be able to do this and can share some tips if needed.
If pipetting into a liquid it’s always cLLD. Low volumes often need a LC with a slightly larger blow out volume and this can cause bubbles at the bottom of the tube/well depending on the fixed height of the dispense. Most bubbles created with cLLD will float to the top and hopefully pop. If they don’t they usually don’t cause an issue with the next aspirate step out of that tube/well.

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I’ve had this experience as well for 8-span. Just be sure to minimize submerge depth so carryover doesn’t affect the volume transfer at very low volumes. I’ve had success down to 1uL pretty easily.

To make it more complicated though - I do find the 10 uL tips to work well with the 96MPH. Not sure what the exact reasons are but it’s what I had to use to get my 384 qPCR setup working.

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Well that’s some top tier information right there. We have two full boxes of the 10ul tips and recently acquired a second Hamilton robot, a Starlet with a 96MPH. I’ll give them a try.

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Let me know if you’d want a LC or example method! It’s pretty basic though, just good precision and some LC calibration offsets

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Thanks so much, I’ll reach out when we start a project that would use them! Right now I’m focused on automating magnetic bead DNA extractions which comes with it’s own host problems to solve. I saw in a previous post today that you have quite a lot of experience with that also; if you don’t mind chatting I’d love to get your input on where the downfalls usually lay.

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I believe this is due to the length of the tips increasing z-deviation (aka straightness) of the tips: longer tips will aggravate pickups with even slight tilts (or potential, though in Hamilton’s case very rare, manufacturing variability).
I have also found that 96-head usage in 384-wellplates is much better with the 10 uL tips.

In my experience this depends quite a bit on additional liquid info (10 uL alone or 10 uL from a larger amount of liquid in the well?) and importantly, plate dimensions:

  • If you want to aspirate 10 uL from a 96-wellplate and want to use Liquid Level Detection (LLD) the STAR’s cLLD should be able to do it for most liquids. Though if you just want to remove that amount of liquid I would recommend fixed height for consistency purposes.
  • If you want to aspirate 10 uL from a 384-wellplate using LLD things change in my experience:
    cLLD requires its capacitance sensor to detect a charge-dissipation/drop-in-charge event based on a specific “sharpness” (angle of charge/time plot).
    My hypothesis about seeing cLLD consistently fail in 384-wellplates with low volumes: the charge doesn’t dissipate effectively enough when the liquid is so narrow (in the x-z, y-z plane).
    → whatever the reason, I found an easy solution:
    use the STAR’s pressure-LLD instead.
    It can be parameterised to detect even tiny liquids with ultra-precision.
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