Exploring Bioelectricity: Reviewing a Circuit Activated by Human Touch

[mdjensen22]

I was asked to review a patent in which a company is claiming their circuit is activated by "bioelectricity".

The circuit appears to be a basic 'line-hum' touch circuit, but just to make sure I was hoping somebody could point me in the right direction.

How much, if any, voltage and/or current is the human body able to produce and sustain to the outside world (transferred through a finger touch)? To clarify, I don't mean in regards to ESD.

 

[NobodySpecial]

Unless you are putting two dissimilar metal electrodes into the body - I would have said zero

 

[Yanick]

The body uses different concentrations of ions inside and outside of the cell to create a membrane potential. From what I know, this voltage cannot really be harnessed to the outside world. Even if it can, the voltages are on the order of mV's. I'm no electrical engineer, and my knowledge of electricity is very limited, but that is pretty darn low voltage.

Here's the wikipedia article, I haven't read it but it looks pretty thorough at a glance. http://en.wikipedia.org/wiki/Membrane_potential

 

[Proton Soup]

there are a couple of ways i can think of right away. one is related to the ESD you mentioned. that is, if someone touches a charged conductor, some of that charge would be transferred to the person. you don't need an actual spark (discharge) to transfer charge like this, just contact. the amount of charge, and therefore current, transferred could be very low.

another thing is that we are all capacitively-coupled to the ground and line voltage around us. it's just a few picofarads, and that means that the 60Hz current we are conducting all the time is pretty low. it really only becomes an issue in medical device settings where invasive probes are involved.

you'll probably get a better answer in the electrical engineering subforum, or maybe seek consulting from a medical device engineer.

but yeah, "bioelectricity" sounds like more of a marketing term here.

 

[mdjensen22]

Thanks guys - you've pretty much confirmed everything I thought.