We have developed quantitative methods for determining constituent
concentration in a continuous (non-batch) processes.  It is intended
for situations where the constituent of interest in an opaque stream
(e.g. blood) is allowed to diffuse into a reference stream by bringing
the two fluid steams together downstream from a micro T-junction.  The
optically detected concentration distribution of the constituent in
the reference channel can be used with an analytical model to back out
the upstream constituent concentration.  This was reported in MicroTAS
'98 "Micro-Fluidic Diffusion Coefficient Measurement" by P. Galambos
and F.K. Forster, pp. 189-192.  The method also has been extended to
the very interesting case of two streams having different viscosity
and different diffusion coefficients and used to show the non-linear
relationship between diffusion coefficient of a constituent in a
polymer and the polymer viscosity.

> -----Original Message-----
> From: Mehmet Arik [mailto:arik@me.umn.edu]
> Sent: Monday, February 15, 1999 3:02 PM
> To: MEMS@ISI.EDU
> Subject: Chemical sensors
>
>
>
>
> Hi to all:
>
> Does anybody know about MEMS devices that can analyze (give the
> concentrations of the chemicals) a chemical mixture ?
> Your time is appreciated.
>
> Thanks.
>
> Mehmet.
>
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>
> Stay cool, Listen CURE, and Have a warm winter
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>