"Continuous" On-the-fly Dispense on Hamilton STAR

Hi everyone,

I am working on a method that requires the plating cells onto an agar plate. An ideal plating would have a uniform coating of cell material across the top of agar. Obviously, this is hard to achieve with a pipetting robot. However, I believe if i could dispense a constant stream of material as I moved the head in X, I could achieve something good enough to achieve my goal. I am picturing replicating something close to this. Perhaps I will have ~8 strips of dispensed cell material in my plate.

So my question is, has anyone achieved a continuous “on-the-fly” dispense through Venus. Any tips/leads are appreciated.

Thank you!

Venus have a command “dispense on the fly”. Only move X axis. But dispense contiuous in the well part area. Video link:DispenseOnTheFly.mpg - YouTube

Yeah, this is close to what I need, but dispensing continuously is what I am really looking for. I tried defining 1536 plate and hoped that the granularity of wells would affectively achieve a continuous dispense. This did not work great. Maybe I can define one large well and that will allow the head to dispense over a larger X window.

Check the following post for more information regarding tips for the DispenseOnTheFly step

What type of petris are you using? Round or Omni tray (SBS) style?


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Hi Nick,

I did see your comments in that thread. A peer also supplied me with a nice guide on the “Dialogue: 1000uL Channel Dispense on the Fly”.

I am using Omni Trays with the goal of making the workflow automation friendly. I am imagining make 8 discrete “stroke” of cellular material on the Omni tray if I can get a continuous dispense to work on the STAR. Would it perhaps be possible to use parallel steps (a move and a dispense firmware command) to achieve this?

Ah. I see your issue. Fortunately you will still be able to use the dispense on the fly step to achieve this, and custom firmware commands will not be necessary.

When you use the dispense on the fly step do deliver a dispense shot to multiple wells within the same row, the plunger temporarily stops between well locations as to not deliver liquid to an anticipated sidewall. In your case, you can use dispense on the fly to achieve continuous dispense delivery/plunger movement over the course of the entire plate by defining the Omni tray as a custom 8-well plate.


This way each channel delivers a dispense shot in a continuous row, one row per channel, with uninterrupted plunger movement.

Using a jet part liquid class with a dispense rate of 200uL/second, the following step parameters worked as a starting point for your application, dispensing 1mL per channel over the length of the tray.

The X speed is critical here. The X speed and dispense rate need to align so that the dispense ends as the channels reach the end of the plate, otherwise errors can be triggered. Also note that the 'Start X-offset parameter is relative to the center of the well (left).

The following link provides a starter labware definition. I don’t have an Omni tray on hand, so this is a generic rck defintion starting point with 8 wells, tailored for this application. You can fine tune to match your specific labware.

DotF template rck - 8 channels

For your particular application and cell suspension, you will likely need to fine tune dispense rate, X speed and volume. If you need more than 8mL to achieve a sufficient coat, then you may need to perform multiple dispenses per plate.

Hopefully this gets you started on a better track.



Thanks Nick! This is awesome and what I was looking for. I am going to attempt to modify what you provided to work with 300 uL tips dispensing 50 uL each. I figure I may run into a X velocity cap with such a low volume, but I will make a custom liquid class that dispenses a little slower to buy time for the x travel. I will post update here.

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I think I have it optimized. Because of my low volume per tip, I can not really achieve a consistent stream for the path length required (a problem I didnt expect), but the results are ok nonetheless. I ended up using a x-speed of 95 mm/s and a long offset of 65 mm to allow for a 40 mm acceleration distance. These setting combined with a slower dispense on the liquid class worked ok.

I will try to use the HHS to sheet out my rows of droplets now haha.

Thank again, Nick!