1. Introduction - 2. Development
Applications - 4. Links
5. Liquid metal Elastic Stretchable wire - 6. Practical issues
Also, see my article on
Why make a Liquid Metal Elastic Stretchable Wire?
The basic advantage of using liquid metal is that the RF can be kept in a straight line for the best (and predictable) velocity factor, inductance, and impedance. Putting the non-toxic liquid metal into a stretchable elastic rubber tube gives you RF performance! It eliminates the problem of the non-toxic liquid metal sticking, because it is ok to stick in this application. You can also use it in almost any position, with certain limitations.
Above is an animated diagram of a stretchable elastic liquid metal wire being stretched out, then "springing" back. In the diagram red is the solid wire, the gray is liquid metal, and the rubber tube is black.
Another application of this idea is to put a balloon inside a balloon,
with liquid metal in between the balloons. Then when you inflate
the inner balloon the liquid metal forms a thin shell. This gives
you an air pressure adjustable antenna element.
Where did the idea come from?
The one annoyance with my first Liquid Metal Antenna efforts is that the liquid metal was being pushed up vertical. Gravity made going downwards or horizontal seemingly impractical. When I thought about using plastic telescopic sections or similar, the ideal of a rubber balloon came to me. A stretchable tube seemed the ideal shape. You might even be able to pump the liquid metal into the stretchable elastic tube! Another possibility was to use a rubber strip or sheet coated with liquid metal, you could stretch it the way that you wanted.
You end up with a good and predictable surface for RF currents as long as the liquid metal flowed smoothly along the surface. Stretchable products with wire woven in them are unlikely to be very useful or predictable with RF.
I did a search
on Google for "elastic stretchable wire" and came up with only 3 hits,
none relating to this application. Changing to "stretchable
elastic wire" on Goggle came up with 0 hits. You can find "elastic
wire" on Google, but "elastic" does not have to be stretchable.
The elastic only wire does not have the amazing stretch properties of the
Liquid Metal Elastic Stretchable Wire.
Development of the Elastic Stretchable Wire and Balloon
Considering the problems with the liquid metal sticking, I thought that I could simply coat a rubber band, add contacts, and go. That damn liquid metal did not want to stick! It would stick when you did not want it to. Though I knew that I could get it to stick eventually, I went straight to testing a rubber tube.
Below is a picture of the first and second Liquid Metal Stretchable Elastic Wires. The red tubing * was all I had at home, so I made a short sample. The solid copper wire is duct taped to the ends, this was just a prototype after all.
The first Liquid Metal Elastic Stretchable Wire
Putting a balloon inside a balloon was easy. When I put the liquid metal between the layers of balloon there were some air bubbles. So when the inner balloon was inflated, you can see some spots without any liquid metal. Most of it still had a good layer of liquid metal inside. The cat approved it.
Liquid Metal Balloon inside a Balloon
Applications of Liquid Metal Elastic Stretchable Wire:
Because of the RF properties, it can be stretched into adjustable length antenna elements. You could connect short sections together to create longer stretchable wires.
Another application is to pump liquid metal into the stretchable elastic tubing using methods discussed in the Liquid Metal Antenna development and applications.
Other than antenna uses, this stretchable elastic wire may be useful for it's other properties. It gets thinner when stretched, so it's resistance will go up for the entire length. You could use it for a "stretch meter" or similar application.
Elastic Stretch Yagi (I will provide photos when I finish one.)
Making it work - development concerns
I stopped working on the other Liquid Metal Antenna experiments while I investigated these ideas. With so many possible uses and tests for the liquid metal I need to recycle between experiments or buy more. The liquid metal that I do have may be slightly contaminated with who knows what by now, but it still seems to be working ok.
I will be dividing my time now between using the Liquid Metal Wire and
the other Liquid Metal Antenna experiments. I have health concerns
to be taking care of also, so do not expect new and constant discoveries.
I am hopeful that other people, like you, will look into experimenting
with theses ideas.
Links & more
Liquid Metal Antenna group on Yahoo!
See the Main page of Ham Domain.com - or - About me on hamdomain.com
I give this information freely, without concern of profit or reward, because I believe in compassion. I wish the world did also.
© Copyright 2016 - Michael John Lake - Make copies for personal
* Red Tubing: The red tubing is actually from a no. 14 FR catheter that I was unable to use or return. SCI patients would understand.