Hi Jeroen,

I have had this problem too, but at higher voltages.
If the voltage becomes too high chlorine gas will be
generated from the chloride ions that attacks the gold.
I would check the voltages with an oscilloscope.
And of course if you have a material under your gold
maybe this is lifted off of your substrate causing
the gold to be "dissolved"

I hope this helps,
Heiko

*******************************
MESA+ Research Institute
      Twente University
         P.O. Box 217
     7500 AE Enschede
       The Netherlands
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-----Original Message-----
From: mems-talk-admin@memsnet.org [mailto:mems-talk-admin@memsnet.org]
On Behalf Of Jeroen Nieuwenhuis
Sent: Wednesday, August 21, 2002 6:30 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Dissolving Gold electrodes


Dear all,

I am trying to measure the impedance of a 1% NaCl solution using 50 um x
150 um gold electrodes (thickness 0.6 um) in a microchannel and the
electrodes dissolve in about 40 minutes(!).

I used very pure NaCl and distilled water to make the solution. I use a
sine-wave generator to make a 50 mV AC voltage (offset oV) and I measure
the current using an transimpedance-amplifier with a 100k resistor. Nor
the source nor the read-out electronics seems to generate a DC value
current.

Does anybody have a suggestion what is going on? To the best of my
knowledge nothing should happen when the AC voltage used is less than
about a volt.

Regards,
Jeroen Nieuwenhuis _______________________________________________
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