Re: Viscosity Effects on FCM Analysis

Dave Coder (
Tue, 17 Jun 1997 17:05:33 -0700

The responses thus far pointing out a decrease in sample velocity as the
sample medium viscosity increases are, of course, correct. (This falls out
immediately from the Reylolds number for the sample flowing in its tube. If
viscosity goes up, then velocity must go down to maintain constant
conditions of laminar flow; an increase in density may offset the viscosity
somewhat. There's a very spiffy web page where you plug in variables for
Reynolds number and see the change. It's at: .)

Hydrodynamics aside, there could be a problem with a refractive index
mismatch of the core and sheath fluids that will affect the direction of
light scatter and fluorescence and consequently, instrument alignment. (I
was reminded of this last week while kayaking on the coast of Vancouver
Island, and watching the blurring effect of a freshwater stream run under
the incoming tide--refractive index mismatch.)

Dave Coder

> From: Ray Hicks <>
> To: Cytometry Mailing List <>
> Cc: Cytometry Mailing List <>
> Subject: Re: Viscosity Effects on FCM Analysis
> Date: Tuesday, June 17, 1997 3:15 AM
> Matt,
> Freyer-JP; Fillak-D; Jett-JH studied the effects of viscosity in a way in
> Cytometry. 1989 Nov; 10(6): 803-6, they used xanthan gum to slow the
> settling of cells prior to passing them through a cytometer. Xanthan is
> thixotropic or pseudoplastic, so although it's thick at rest, it flows
> easily under stress. How does your viscous medium behave?
> Another problem that might occur before you reach the point that your
> suspension won't go through the nozzle is that there may not be enough
> stress from the sheath to bring about hydrodynamic focusing or stretching
> of the core to produce the spatially constrained single file of cells
> we all know and love, you might get around this by upping the sheath
> pressure (you might need to increase sheath viscosity to prevent
> turbulence).
> On that last point, has anyone studied the effects of sheath viscosity
> core stability (and sample cv's) at high flow rates?
> Ray
> ISSN: 0196-4763At 8:17 am -0400 16/6/97, Matthew J Shaw wrote:
> > All,
> >
> > Does anyone have a good feel for the effects of higher viscosity
> > fluids being analyzed via flow cytometric means? For example, the
> > viscosity of water is 1 centipoise, and I assume that cells that
> > within water can be reliably analyzed. I believe that the
> > of blood is perhaps 3 centipoise; again, I assume that cells within
> > this matrix can be reliably analyzed. However, if the matrix is
> > 10 centipoise, there may be a problem with forcing the matrix
> > the FCM nozzle. Maybe a problem doesn't exist until the matrix is
> > centipoise? Has anyone done a study like this on any flow
> > or have a good feel for this effect? What is the upper viscosity
> > limit before any problems may occur? (I realize that one could
> > the sample with a low-viscosity liquid until the desired viscosity
> > reached - I'd rather not have to do that!) I would appreciate any
> > on this matter.
> >
> > Matt Shaw
> Ray Hicks
> ________________________________________________________________________
> |University of Cambridge |Tel 01223 330149 |
> |Department of Medicine |Fax 01223 336846 |
> |Level 5, Addenbrookes Hospital |e-mail <> |
> |Hills Road Cambridge |Web |
> |CB2 |ftp server |
> |UK | |
> |_________________________________|_____________________________________|

Home Page Table of Contents Sponsors E-Mail Archive Web Sites

CD-ROM Vol 3 was produced by Monica M. Shively and other staff at the Purdue University Cytometry Laboratories and distributed free of charge as an educational service to the cytometry community. If you have any comments please direct them to Dr. J. Paul Robinson, Professor & Director, PUCL, Purdue University, West Lafayette, IN 47907. Phone: (765)-494-0757; FAX(765) 494-0517; Web , EMAIL