Friday, August 01, 2025
We have the PEGDA
The PEGDA has arrived. For those catching up, this is the main component of a UV curable resin that polymerizes as a stable ionic gel. What this gets us is a way of creating electronic devices using μRepRap's fabrication abilities. These devices won't be the super fast silicon sort of things, but rely on migrating ions into or out of gel structures to change their electrical characteristics.
These structures should be stable in themselves, but for long term use I'll probably encapsulate them in standard UV resin to isolate them. There are though a few other chemicals needed to do these tricks, some of which can be re-purposed from more readily available pharmaceuticals, and others which might need a bit of kitchen chemistry.
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Very, very interesting. If you have time can you write up a more detailed post on how PEGDA might be used to create electronic devices.
The plan is to mix up something along the lines of:
[Component] [Purpose] [Amount]
PEGDA Main gel network 75%
Choline chloride Ionic dopant 5–10%
eSun resin UV photoinitiator 15–20%
Glycerol (optional) Humectant/softener 0–5%
to create a stable, non-drying resin that solidifies into a gel that is conductive and chemically porous to ions. Then to use copper/gold traces (which I think I can adhere to the slide using semi-gelled resin) to drive copper ions into the gel using electrolysis. A third trace would act as a sense wire, effectively measuring the increase in conductivity provided by the ions. This would work in a similar way to a FET.
By reversing the flow, the gold- or carbon-based electrode would not introduce ions, and the copper ions would migrate out. The resistance of the cell would then increase.
You could view this as being a sort of switch, or non-volatile memory cell. Of course, some driver circuitry would be needed to demonstrate this, and creating an array would have a few issues with parallel conductors activating adjacent cells, but that for later experimentation.
Another interesting side-shoot (like I need more of them) would be to add an indicator to the gel that changes colour with the presence of the ions (or some other reaction by-product). Then you get a colour-changing cell. Oooo! A pixel!
[Component] [Purpose] [Amount]
PEGDA Main gel network 75%
Choline chloride Ionic dopant 5–10%
eSun resin UV photoinitiator 15–20%
Glycerol (optional) Humectant/softener 0–5%
to create a stable, non-drying resin that solidifies into a gel that is conductive and chemically porous to ions. Then to use copper/gold traces (which I think I can adhere to the slide using semi-gelled resin) to drive copper ions into the gel using electrolysis. A third trace would act as a sense wire, effectively measuring the increase in conductivity provided by the ions. This would work in a similar way to a FET.
By reversing the flow, the gold- or carbon-based electrode would not introduce ions, and the copper ions would migrate out. The resistance of the cell would then increase.
You could view this as being a sort of switch, or non-volatile memory cell. Of course, some driver circuitry would be needed to demonstrate this, and creating an array would have a few issues with parallel conductors activating adjacent cells, but that for later experimentation.
Another interesting side-shoot (like I need more of them) would be to add an indicator to the gel that changes colour with the presence of the ions (or some other reaction by-product). Then you get a colour-changing cell. Oooo! A pixel!
Super cool - opens up a lot of possibilities. I'm sure I'm not alone in looking forward to seeing an implementation of this.
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