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Skimmer-reducer lifetime

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AMitch

Contributor

Posts: 21

Joined: Mon Nov 24, 2014 12:40 am

Post Mon Apr 03, 2017 6:21 am

Skimmer-reducer lifetime

Hi All,

Six months ago we had a Helios installed and it now looks like skimmer reducer assembly is going to need replacing. It's only had light to moderate use - a shade under 300 hours of plasma running time. Previously, on two CyTOF2 instruments I've had significantly more run time before needing to replace the S/R, so I'd really like to hear what others' experience with S/R longevity on the Helios is. Is failure after this much use normal?

Also - basic question - what are the major factors influencing cone lifetime? The only thing I could think of is maybe use of HNO3/HF for cleaning causing erosion. Any thoughts/comments appreciated...

cheers,

Andrew
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AMitch

Contributor

Posts: 21

Joined: Mon Nov 24, 2014 12:40 am

Post Thu Apr 06, 2017 11:00 pm

Re: Skimmer-reducer lifetime

Following up from my own question...

One thing that has been obvious on moving from the CyTOF2 to the Helios has been the need for higher current values. On the CyTOF2 this started at around 4-4.5 and after a lot of use it reached about 8 or so, at which point the skimmer/reducer wasn't looking the greatest. With the Helios our one experience is that the current reached 8 after about a month and hthen to ~9 by about 3 months with the S/R wtill looking, well, pretty good actually. The official advice I have is that the S/R hits this value it needs to be replaced. I've had offline discussions that these sorts of values are normal for the Helios, and at least some labs are only replacing S/R assemblies well beyond 10 (requiring this limit to be increased in service mode).

It would be good to know others' experiences. At what point do you replace? Any and all comments appreciated!

Andrew
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mleipold

Guru

Posts: 5792

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Thu Apr 06, 2017 11:25 pm

Re: Skimmer-reducer lifetime

Hi Andrew,

I know that Helios instruments definitely run at a higher Current. This happens with out-of-the-box Helios. It *also* happens with v2-to-Helios upgrades (I know of at least two instances); since the cones are not typically changed during the upgrade, this means it has to happening because of something involved in the upgrade itself. From some discussions I've had, most likely it's due to the Helios injector doing a better job of focusing the cell events into the plasma and therefore more on target into the cones. If so, then the skimmer-reducer (which is affected by the Current value) might need more Current to "steer" the ions into the instrument.

I know that some people are putting Helios injectors into their v2 instrument; I would be curious to hear whether they also notice a jump of ~2 units in Current.

For v1 and v2 instruments, I agree, a brand-new shiny skimmer-reducer should start out in the Current = 3-4.5 range. By the time they get to 8-8.5, they're usually in need of a change: ; it was usually physical damage that would make you need to swap them out (non-centrosymmetric orifice, overly widened orifice, physical chipping/pitting, etc), rather than maxing out the Current = 10. So, 4-5 Current units of lifetime, *easy*.

In a year and a half of Helios instruments, we've replaced the cones on each, once. For Helios instruments, you generally have a starting Current value ~7-8 for a shiny new cone right out of the packaging. Which, if you have a max Current lifetime = 10, would mean you only have 2-3 Current units of lifetime.....I don't think that's correct.

After only 2-3 months or so, we had hit Current = 10, and our Tb and Tm Duals continued to decrease. Fluidigm was insisting it was a skimmer-reducer problem, I insisted a remote session to check. When the Fluidigm Markham engineer remoted in, he did a Current Sweep (like you used to be able to do in v1 and v2) and noticed that the Current hadn't peaked during initial Tuning. Looking at the full sweep, the Current optimum was ~11 (ie, one unit above the software upper limit).

So, he increased our upper limit to Current = 15, and we've been fine ever since (after Oct 2015): the Tb and Tm went back to where they had been with the new installation, etc. In my case, the skimmer-reducer needed to be replaced in the 12-13 range, which would be the typical 4-5 Current units of lifetime. We replaced another one this week, which had reached Current = 11.5.


In short: in my experience, Helios skimmer-reducers need higher Current, and therefore the upper limit of your Helios *should* be ~15, not the default 10....they're definitely usable above 10, and at a few thousand dollars apiece, aren't a component you want to replace too often if you can avoid it!


Mike
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AMitch

Contributor

Posts: 21

Joined: Mon Nov 24, 2014 12:40 am

Post Fri Apr 07, 2017 12:23 am

Re: Skimmer-reducer lifetime

Hi Mike, thanks for the comments.

An observation relating to your comment on swapping the Helios injector into a CyTOF2. We've actually done the reverse of this when we had a broken Helios injector and had to run with our old CyTOF2 piece while we waited for spares to be shipped to Australia. The optimum current didn't actually seem to change either on the Helios->CyTOF swap or when we swapped back. Just n=1 of course. A marked difference in the size of the ion clouds though.

Andrew
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netgnomemom

Participant

Posts: 3

Joined: Thu Aug 31, 2017 4:36 pm

Post Fri Feb 16, 2018 4:58 pm

Re: Skimmer-reducer lifetime

I've noticed that the skimmer reducer nuts (2mm hex wrench) loosen up over time with sonication. I found that if I took the skimmer/reducer apart (careful with the o-ring, it's fragile) cleaned it inside and out and put it back together I can increase the life span significantly. I also tighten those nuts each time I pull the skimmer/reducer out of the sonicator.
Hope this helps some.
Christine
university of colorado Cancer Center Flow Cytometry Shared Resource

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