[Neuroscience] Re: Fast drug application 'liquid filament' help!

Bill via neur-sci%40net.bio.net (by connelly.bill from gmail.com)
Sun Jul 22 02:24:58 EST 2007


Yeah, I've ended up with a lot of different needs because our lab is
kinda split in two, a brain slice - academic - real science end, and a
corporate, contract research, cell culture end. And for some odd
reason I've ended up being in charge of both, probably something to do
with have a professor who is also HOD of a department full of people
who would rather squabble than do any work.

Honestly, thanks a whole lot for the advice. I'm really surprised by
how little information there is on this. Usually the places that sell
these kind of things show you exactly how you would use them (usually
to encourage you to buy everything from them), but the physik
instrumente site just gives you technical specs.

I'll look into the 'bimorph' option as well.

Thanks again.


On Jul 19, 10:18 am, jonesmat <jones... from physiology.wisc.edu> wrote:
> On Jul 16, 5:31 pm, Bill <connelly.b... from gmail.com> wrote:
>
>
>
> > Hi,
>
> > Does anyone here use a liquid filament style, fast drug applicator?
> > E.g. theta pipette with control and drug in each barrel, which is the
> > rapidly moved via a piezoelectric actuator to squirt the drug solution
> > onto the cell?
>
> > Does anyone have any brands they could recommend?
>
> > I'm also a big confused about how the whole setup would look.
> > Obviously you'd need a course manipulator to get the pipette close to
> > the cell, some kind of pipette holder, and the piezoelectric stepper.
> > You'd presumably mount the manipulator to your isolation table, and
> > then the actuator onto the manipulator?
>
> > Thanks for any advice.
>
> Geez Bill,
>
> You seem to have one finger in every possible pie, from hippo to
> thalamic slices to fast application to who knows what else.
>
> As it happens, we routinely use piezo-driven fast application.
>
> Assuming you want to make real fast, submillisecon solution exchanges,
> suitable for studying, say, AMPA or GABAA receptor kinetocs, there are
> two basic flavors. If you don't need to be that fast, then there are
> probably more options. We do the former, and I have used both flavors.
>
> Flavor A > Very fancy, very fast, very expensive:
> This would be a large piezo-electric element, typically several
> centimeters in length and 2 cm in width, either made of a "stack" of
> smaller piezo disks or a single cantilevered block. They are made by
> Physik Instrumente, and by Burleigh. In either case, from the outside
> it'll just look like an aluminum bar or cylinder with a 3 mm diameter
> cable hanging out the back, and someplace to screw in a small pipette
> holding attachment. You can mount it approximately the same way you
> would mount a headstage (but there are some additional vibration
> issues to worry about, because the headstage doesn't recoil, whereas
> this thing most definitely does). These are driven by very strong
> voltage sources (> 1000 volts), they usually move extremely fast, but
> they also usually have a quite limited degree of total movement (200
> microns max?). One would mount the flowpipes or theta tube to the
> front end, via a little screw-clip or something, which can be easily
> homemade, or probably purchased at exhorbitant cost from the company.
> The lateral movement of the pipette is executed via a piston-like
> movement of the piezo, at least for the Physik stacks.
>
> Flavor B > Not fancy at all, very fast (but not as fast), relatively
> cheap:
> This is what I prefer. I routinely get 200 microsecond 10-90% solution
> rise and fall-times, so definitely fast enough for rigorous kinetic
> work most of the time. However it's largely homemade, so if you're
> looking for plug & play technology and have a large budget, go with
> the Physik or Burleigh systems.
>    Here the piezo element is a little tiny wafer-thin chip called a
> "bimorph", about 10 mm x 20 mm x 1 mm. These are bought separately
> from Morgan Electro Ceramics, and only cost $35 each. BUT, Morgan now
> has a $3000 minimum limit, so you would probably want to split a batch
> of 80 bimorphs between a few different people. You can use the same
> bimorph for a year or more if you take good care of it (which means,
> don't bash it with anything). Eventually they wear out after many tens
> of thousands of steps.  You have to solder leads to this yourself to
> connect to a voltage or current source. We use a linear amplifier from
> WPI so we can give bidirectional steps, and control the degree of
> motion in an analog manner. We need to do this because we are often
> hopping between more than two pipes (usually 3-4, depending on the
> specific expt, see J. Neurosci. 18:8590 for some examples of complex
> step protocols). You usually can't do this easily with Flavor A,
> because of the limited motion. Anyway, the bimorph only needs tens of
> volts, so any old SIU can be used to drive it, especially if you only
> need two barrels. The bimorph is mounted by clamping the back corner
> with whatever clip is handy and sturdy. A black binder-clip would
> actually work. You have to make your own piece for holding the
> pipette. I use a tiny piece of perspex that I cut a groove in with a
> hacksaw, then tapped some holes for small teflon screws to clamp the
> pipette down with. This is then epoxied onto the front end of the
> bimorph.
> The bimorph bends when you apply a current or voltage, so the total
> movement of the flowpipes basically just depends on how long they are.
> You can get several hundred microns of movement easily, which is
> useful for multi-barrel expts on patches, or expts when you want to
> perfuse micro-islands with whole neurons and dendritic arbors growing
> on them.
>
> Both of these flavors have their own drawbacks, and regardless of what
> I said about plug & play before, there WILL be significant fiddling
> around required in order to a) get the solution exchange into the
> submillisecond range while simultaneously b) avoiding the phenomenon
> of "ringing" (wiggling of the pipette movement due to applying a very
> rapid jerky step). Lots of different tricks may come into play here,
> which will be different depending on what system you use.
>
> Cheers,
>
> Matt




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