Here is some information on what I have found out about the micro pH
sensors.

World precision Instruments, www.wpiinc.com has a needle type of pH
electrode and various pH meters available.  The needle is 700 microns in
diameter and 1 cm long.

> ISFETs can be provided by: Sentron Europe bv
> >PO Box 125, 9300 AC Roden, The Netherlands. Sentron has most probably
> also a
> >US agent.  www.industry.ch/sentron
>
> They might be available commercially, but if not we could build
> one on a chip for you. We make chemical field effect transistors that
> are
> essentially voltametric electrodes. Let me know if you want to discuss
> it
> further.
> regards J.Dubow, JOEL.DUBOW@m.cc.utah.edu
>
> Ultra small pressure sensors are being made by RADI, Uppsala, Sweden.
> The
> sening surface is 100*100 µm. Check also our homepage for more
> information
> Wouter van der Wijngaart
> Kungl. Tekniska Högskolan     Tel:    +46 - (0)8 - 790 66 13
> S3, Elektrisk mätteknik       Fax:    +46 - (0)8 - 10 08 58
> 100 44  Stockholm             Minicall:       +46 - (0)740 - 26 71 28
> Sweden                        e-mail: wouter@s3.kth.se
> http://www.s3.kth.se/instrlab/staff/wouterw.html
>
>
>
~~~~~~~~~~~~~~~~~~~
Dr. Alex Freeman
Engineering Manager, Etch Group
Ball Semiconductor, Inc.
972-359-2442
afreeman@ballsemi.com
~~~~~~~~~~~~~~~~~~~