No batteries required

Dave Wilson explains how a ‘potato powered’ LCD clock excited some young children a long long time ago.

<b>’Every adult needs a child to teach, it’s the way adults learn.’ -Frank A. Clark.</b>

Years ago, when my children were so much younger than they are today, I decided to introduce their inquisitive little minds to the concept of electricity by purchasing a small clock that was ‘powered by potatoes’.

The potato-powered clock certainly did what it said on the packet. And I was, of course, well armed with the answers to the inevitable questions that ensued – explaining, as I recall, in some intricate detail, just how the electrodes and the potato worked in harmony to create the potential that generated the current to power the tiny liquid crystal display. They were enthralled.

In ten years time, or perhaps even sooner, my children might have children of their own. And I’d like to think that, if and when they do, they will also be able to introduce their children to the concept of electricity by some latter day version of the potato clock.

Well now, thanks to those clever chaps at Microsoft they might just be able to. You see, those smart fellas at the US software giant have recently patented a method by which the human body itself can be used as a means to transmit power and data.

So it’s possible that in years to come, children might be introduced to the idea of electricity by having small devices like watches, audio players, and personal data assistants, coupled to their bodies by a pair of electrodes that contact their skin.

If the Microsoft dream becomes true, these devices will be powered by a pulsed DC signal or AC signal that’s bussed to each of the devices through the body. The different devices will be selectively powered by using multiple power supply signals of differing frequencies. For example, a 100Hz signal might be used to power a first device while a 150Hz signal may be used to power a second.

Digital data and other information, such as audio signals, will then be modulated on the power signal using frequency and/or amplitude modulation techniques.

Goodness me! Can you imagine the look of delight on the children’s faces as their parents are asked to deliver a treatise on the modus operandi of the Microsoft near field intrabody communication technique. I know I can’t.

But I bet by now you’re wondering whether the child’s body will actually be used to generate the power for the devices as well.

Well, I’m afraid not – exactly. However, because all the devices are networked, they CAN be recharged and powered by other devices on the network such as kinetic converters worn in sneakers and in wrist watches. These, of course, can convert the kinetic energy of the user to electrical power and then distribute that power to devices on the network.

I must say that I for one was somewhat relieved to hear that the power won’t come directly from the body. Because I still remember what the potato in the clock looked like after a month of continuous use. And it wasn’t all that pleasant, I can tell you.

<b>An electric response</b>

Sir:

I am a well known electronics writer and designer – in fact the most widely published in the world during the past year. In a forthcoming article (scheduled for publication), I make a passing reference to using trees to transmit and receive. And I myself have done a number of designs which detect the body’s electric field – one of which described, among other things, how to approximately estimate body weight with a handshake. At that same time, my son and I discussed data transmission through a handshake – close!

But what would concern me is using the body for anything electrical at all. My latest major project (EPE Wart Zapper / N&V Wart Remover) destroys warts with 100µA pulses. Its broad significance is that it uses about 1,000th of the power of electrodesiccation units in use in clinics today. As one example of the hazards of mixing the body and electricity, take a look at the photo.

During experiments to determine the correct ‘exposure’, I applied 60µA pulses to a finger, 70mm – nearly three inches – away from this fingernail. I came away from my experiments with a new respect for electrical currents in the body, no matter how small.

One of my projects (Pot Plant Power) tapped power from plants. The power was miniscule, but sufficient to ‘light up’ a potato clock – power apparently generated by plant DNA. I have a theory, although I haven’t found any volunteers to test it yet, that with an earth wire, and a probe stuck into living human flesh, it might be possible to do the same.

Thomas Scarborough

<b>The editor replies:</b>

Thank you for sharing that with the readers. Since the editorial was written, it seems like everyone is getting in on the intrabody communication act.

The New Scientist magazine has reported that a German company by the name of Ident Technology has now actually developed several prototypes of a system that transfers a tiny electric current across the skin. One system is incorporated into a pair of safety goggles and sends a signal to a corresponding electric drill. This means the drill only switches on if the operator is wearing the protective goggles.

You can read more by clicking <link>here=http://www.newscientist.com/news/news.jsp?id=ns99996247&lpos=home5</link>.