Re: Static Charge on Sort Collection Tube

From: Howard Shapiro (hms@shapirolab.com)
Date: Mon Nov 25 2002 - 22:35:09 EST


Larry Polsky wrote-

>As a newcomer to sorting, I would appreciate any thoughts or comments on
>the need for inserting a static drain wire into non-conducting
>sort-collection tubes.
>
>There are references in the literature (see below*) that note the
>possibility of sorted droplets being repelled by static charge that can
>accumulate on non-conducting, plastic collection tubes. The suggestion
>made in these references is to insert a grounded drain wire into the
>collection tube to dissipate any charge. However, two experienced sorters
>who I have asked about this have not seen static accumulation to be a
>problem and do not use drain wires.  The suggestions have also been made
>to use glass tubes (not always possible) or to coat non-conducting
>collection tubes with serum to achieve the same result.

The droplets you sort are charged. If you sort them into a nonconductive
vessel, they stay charged (you can pick up a shock by dipping your finger
into a weight boat full of sorted droplets, but it's kind of hard to get a
finger into one of the small tubes typically used for sorting). Once you
accumulate a pool of charged droplets, they tend to repel droplets of like
charge. I don't sort much, but when I have done sorts, I have noted some
strange behavior of droplets, which seemed to go away when I used a
grounding wire. If you are not inexplicably losing cells, you probably
don't need to bother with grounding. If accumulated charge got to be a
problem, the best solution might be to have collection tubes made of
conductive plastic.

-Howard



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