Dear Vishwa,

I am also working on PIV. I use 0.05% by volume of Tween 20 in DI water. I
can obtain monodisperse suspension of beads. This adding also prevents
non-specific binding of beads to glass substrate. Please refer to this
paper:
http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=4388308&arnumber=4388434&co
unt=386&index=125

Hope this help
Nam Le
Ritsumeikan University


On Fri, Feb 22, 2008 at 5:44 AM, Kirt Williams 
wrote:

> Start with 0.01% Tween-20 by volume (e.g., 100 uL Tween-20 in 1 L of
> water).
> According to a paper I've seen, concentrations greater than this do not
> lower the surface tension, while concentrations lower than this result in
> higher surface tension. From experience 0.01% is nice enough to work with,
> while 0.1% produces more foaming.
>     --Kirt Williams
>
> ----- Original Message -----
> From: "Vishwa" 
> To: "General MEMS discussion" 
> Sent: Thursday, February 21, 2008 9:24 AM
> Subject: [mems-talk] How much Tween 20 to add
>
>
> > Hi,
> > I am running some microPIV expts in a channel, the dimensions of which
> are
> > 50mm * 2.5mm* 45um. There ends up being a lot of bubble formation in the
> > channel and I was advised to use some surfactant like Tween 20. I bought
> a
> > bottle of that. But it doesn't come with any guidelines and to how much
> > should be added. I would appreciate if you could tell me some number as
> a
> > safe starting point.
> >
> > The flow tracers that I use are carboxylated polystyrene beads in
> nanopure
> > water.