Making Cavity Microelectrodes: Overcoming Setbacks

[rloughlin03]

I am attempting to make a cavity microelectrode in which i will test the electro chemistry of polyaniline powder before moving on to other chemicals. I have read numerous papers on the subject. I am having a major setback in my aim: i need contact between my gold wire and the voltameter (as shown in the diagram). I originally tried mercury, but forgot that it would dissolve the gold. I am thinking of either one of three things: a graphite powder, soldering the Gold wire and copper wire together, or finding another low m.p. metal to use. I would really appreciate any ideas or feedback, especially from those who have made cavity electrodes before.

Thanks

Ryan

P.S. apologies for the crude diagram, done in a rush. Just trying to help "paint the picture"

 

[chemisttree]

I am attempting to make a cavity microelectrode in which i will test the electro chemistry of polyaniline powder before moving on to other chemicals. I have read numerous papers on the subject. I am having a major setback in my aim: i need contact between my gold wire and the voltameter (as shown in the diagram). I originally tried mercury, but forgot that it would dissolve the gold. I am thinking of either one of three things: a graphite powder,

Not so good...

...soldering the Gold wire and copper wire together,

solder - yes
Copper to Gold - why?

... or finding another low m.p. metal to use. I would really appreciate any ideas or feedback, especially from those who have made cavity electrodes before.

Thanks

Ryan

P.S. apologies for the crude diagram, done in a rush. Just trying to help "paint the picture"

For what you are intending, isn't a 4-point probe a better choice?

 

[rloughlin03]

Got good results using a platinum wire, with a mercury contact. Obviously any redox potentials on the surface arent desireable, but results are looking to be fine in comparison to previous works in the field. I was able to integrate the curve and get a value for Q, which following on i was able to find the mass of PAN in the cavity and various other info about the cavity.

I have decided to use solder, The M.P. of the solder i am using is around 200-300°C less than the glass, so we've decided to cut up some of the solder, and will heat up the tube to melt the solder for a contact between the wire and Au.If the results don't work, I think i may just go forward with platinum and not gold.The gold would be handy as there is not redox chemistry at the cavity, but needs must...

decided on an iron wire,instead of copper. its just some sort of metal which we can use to connect to the voltameter, no need to use loads of Pt or Au.

We decided just to use a 3 point probe as it was used in a few of the papers we researched. Since then the 4-point probe has popped up a fair bit, but as the results we go were good we are goin to try and continue with what we've got.

Have you done much research in the area? Any advice on what you tried, or even any paticular research papers you used would be appreciated greatly.

 

[chemisttree]

I did some synthetic work on liquid crystal conducting organic compounds based on n-hexylsexithienyl compounds. Others in my lab were studying thin films (grown on QCM). I also did some brief synthetic work with soluble polyphenylene polymer precursors. Back then the 4-point probe was the state of the art. Been away from it too long to be of much more help to you, though.