HBC: Human Body Communication

This was an interesting paper. Turns out that we resonate at around 45 MHz without shoes on and 50 MHz with shoes on. The author of this study has found that by putting a low permeability coil around soft tissue in the ankle and applying a 1 mA signal can possibly be a way for humans to transmit signals like a monopole antennae. He is proposing that this be explored for future wireless devices. A lot of the study went on to show that this process is harmless to the body.

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SomeMichGuy · M

If it's surface waves waves, perhaps, but how skin reacts to being used that way all the time @ ν = 45 - 50 Mhz might well surprise us...

For any exposure to something, incl. EM exposure, the amount of exposure is important; "always-on" exposure is the worst.

Tastyfrzz · 61-69, M

@SomeMichGuy No idea. Apparently rhe body radiates it away with very little temperature rise. I'd think you'd get cooked but the current is low and the grounding must be closed circuit in the body. He shows the circuit diagram in the work.

SomeMichGuy · M

@Tastyfrzz Oh, you'd take a lot to COOK a body, but there are curves for EM exposure, which is a different consideration.

If you figure ppl are a fraction x of water, boiling all the water in a person of mass M, starting at temp. T_0, would take an energy

E_{T_0 -> T(100° C)} =
(xM) * c_{H2O} * (T(100° C) - T_0)

to raise water of mass xM from the starting temp to the boiling temp, plus

E_{phase change} =
(xM) * h_{vap} = (xM) * 2.257 kJ/kg

where
c_{H2O} is the specific heat of water at 1 atm (a function of T); and

h_{vap} is the specific heat of vaporization required for the phase change from liquid to gas.

[For a person weighing 125#, and x ≈ 0.6 (60% water), the energy of the phase change alone is

0.6 * (125# * (1 kg/2.2#))
* (2.257 kJ/kg)
= 76.9 kJ ]

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