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I'm not sure how to phrase this question, but maybe some of you have done research with this...

I am doing some measurements on wireless body area networks, which involves putting sensors on human bodies and transmitting. Now, I can put them on living humans, but if I could somehow "model" a body instead, it would provide more repeatable data. Also normal humans breathe.

Anyway, I think I saw some paper mention certain material properties in simulation, and I might attempt to find materials with those properties (and just wrap a bucket or something). But if anyone has any ideas that would be much appreciated...

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    \$\begingroup\$ They use pig carcasses for testing guns and bullets; why not use one of those. If you're quick you get the added benefit that you can eat some of it afterwards (religious beliefs put to one side of course). Will it be OK frozen? \$\endgroup\$ – Andy aka Oct 2 '13 at 17:26
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    \$\begingroup\$ Well basically we are bags of salty water but if you're trying to find an appropriate analog (specifically for your wireless) why not set up up a few experiments with a 'real body' as a reference and see what gives you the same measurable results. \$\endgroup\$ – JIm Dearden Oct 2 '13 at 17:44
  • \$\begingroup\$ ... about 0.9% salt by weight. Should mimic the conductivity and absorption properties of tissue fairly well. \$\endgroup\$ – Dave Tweed Oct 2 '13 at 18:05
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    \$\begingroup\$ Where's @ScottSeidman when you need him? \$\endgroup\$ – The Photon Oct 2 '13 at 18:10
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    \$\begingroup\$ Interns and grad students are really good materials to emulate human bodies. \$\endgroup\$ – travisbartley Oct 3 '13 at 1:58
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You got some great suggestons in comments. You're looking for a good "phantom". It's going to depend very heavily on what signals and electrical properties of the body you're interested in. Assuming you're interested in some sort of electromagnetic properties that might interfere with your network, I'd look first at some sort of animal carcass. Another thing to consider would be a big porous sponge (like a carwash sponge) soaked in saline (0.9% as mentioned in comments). I've had students use that for electrical stimulation studies (electroporation, specifically). A Phantom for skin would be a bit tougher to implement, maybe thin leather, or maybe even a balloon, but neither would be real close in terms of resistive properties. I suspect for wave transmission, a balloon might be good enough, as the "bag of water" will dominate behavior.

Of coarse, there's all sorts of gelatins for the physical properties. I've seen ballistic gelatins and even the sorts of materials used for fishing lures used.

This paper talks about many more options for very accurate phantoms. http://uwcem.ece.wisc.edu/pdf/lazebnik_pmb05.pdf

Generally, though, if the circuit isn't dangerous, I'd just recommend using people. Yes, we breathe, and so will all your users. Try a spectrum of body types. If you notice problems, then you might choose to move to a phantom.

Things may change a bit if you're trying to measure biopotentials, and you need to generate the potential and watch it propagate through the body. If so, let me know and I'll try to edit.

As a last point, sometimes a bit of finite element modeling can go a long way toward validating a biological phantom.

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  • \$\begingroup\$ Thanks @Scott Seidman! I don't know why I couldn't think of the word "phantom". Anyway, that makes sense. I am leaning towards just recruiting a few of my fellow grad students and doing the measurements at this point. I will check out the paper you linked in case I run into reproducibility problems. Thanks again. \$\endgroup\$ – Mewa Oct 7 '13 at 17:25
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When I was working on Pagers, and commuting to work on my pet dinosaur, we used a "Salty" for on body radiated measurements. This was an Acrylic tube about 18 inches in diameter and 6 feet high, filled with a pretty specific concentration of salt water. This was reasonably repeatable, which was key. We also had a bunch of people stand out on the antenna range for some correlation studies, and came to the conclusion that it was a reasonable way to go.

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  • \$\begingroup\$ This is interesting, and fits some assumptions I was making in my model. I will keep it in mind if the human volunteers don't work out :) \$\endgroup\$ – Mewa Oct 7 '13 at 17:26
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You could measure yourself and model accordingly. Measure your resistance over the appropriate length with an ohmmeter (~4-20M) and model the body as a resistance. You could also measure capacitance and inductance. The will vary widely depending on how much sweat is on the surface of the skin, but you could model the low and high ranges and get an idea of the performance of your circuit.

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