0.5mm Platinum wire
abachman
Posts: 3
Is there any reason the platinum wire needs to be so thick? Could a thinner wire, say 0.2mm, be used instead if it is anchored to some sort of framework to hold its shape?
Comments
https://docs.google.com/a/uconn.edu/file/d/0B6RE82086JGFLWxGWUJmelBpZkk/edit?usp=sharing
Just finished building this 10 minutes ago. It's curing now. That's 0.2mm Pt wire, with a plastic backing I cut out of the bottom of a Petri dish.
https://docs.google.com/file/d/0B31uUgq_S0peRG15NGUxbUY0VDg/edit?usp=sharing
obviously I will have to replicate this in the 60 mL Nalgene container...
During electrophoresis, we overheated it so much that it melted and burned the acrylic and melted some of the solder, but it still works. I do wonder if the anode was used up a bit. It seems thinner.
https://docs.google.com/file/d/0B17LGx-XhonYblFvWDZtVmpqTTQ/edit?usp=sharing
@MNG nice setup. I'll have to look into that aquarium silicone.
FYI, We also built a chamber with stainless steel plate electrodes - not a good idea, as at a minimum we expected the current to leach chromium in to the buffer, however the full 5 liters was a thick rust color within 60min of starting.
The next electrodes will be carbon. Should have that started in the next few days.
We have also changed the box to use an internal snorkel to pull from the top of the chamber and funnel the effluent to the bottom of the chamber and exit. This negates the need to cut and glue the lid, simplifying construction. The chamber does not tip over or have to be secured because of a hose on the top.
Did anyone had luck with other materials? or overcame the dissolving/blackening issue?
If so, do you have advice about the characteristics to look for? I found a site that sells Pt wire at a reasonable price and describes the diameter, purity and 'temper' of the wire but not the resistence. Does anyone know what hard tempered wire is and whether it will perform well in this application?
To answer your question about temper, you can think of the temper of wire like taffy (kind of like a cylindrical Starburst).
When wire (or taffy) is "annealed" (heated), it gets softer. When you pull the ends of it, it will stretch a lot (i.e., it has high "elongation"). And you don't have to pull very hard before it eventually breaks into two pieces (i.e., its ultimate tensile strength is fairly low).
When wire is drawn through a die (i.e., pulled through a small circle to make its diameter smaller), it gets harder. When you pull the ends of harder temper wire (or cold taffy), it won't stretch very far (i.e., it has low elongation). And you'll have to pull the ends using a lot of force to get it to break into two pieces (i.e., its ultimate tensile strength is fairly high).
To keep drawing wire down from a larger size, it occasionally needs to be annealed (heated). There are various standard American Wire Gauge (AWG) sizes. 0.5 mm is roughly equivalent to 24 gauge on the AWG scale. To get "one die hard" 24 gauge wire, you would anneal it at 23 gauge (0.573 mm) and then draw it through the 24 gauge die. To get "two dies hard" 24 gauge wire, you would anneal it at 22 gauge (0.644 mm) and then draw it through the 23 gauge die and then the 24 gauge die. And so on.