Chemical "Infofuses" Communicate Without Electricity

Al writes "Researchers at Harvard and Tufts University have developed a way to send coded messages without using electricity. David Walt, professor of chemistry at Tufts, and Harvard's George Whitesides have developed 'infofuses' that can transmit information simply by burning. The fuses — metallic salts depositing on a nitrocellulose strand — emit pulses of infrared and visible light of different colors whose sequence encodes information. They were developed in response to a call from the Defense Advanced Research Projects Agency for technologies to allow soldiers stranded without a power source to communicate. In the first demonstration of the idea, they used the infofuses to transmit the message look mom no electricity." Currently the researchers are "trying to figure out a way to dynamically encode a message on the fly in the field without specialized equipment."

Comments

cause...

[Random2]

cause, you know...sending smoke signals when stranded in enemy territory is really going to help you....

Weird

[pete-classic]

Step 1, smoke a cigarette under a poncho. Step 2, light an "infofuse". Step 3, get shot in the face.

My Drill Sargent demonstrated how easy it is to spot someone smoking in the dark.

Is a crank-powered radio really out of the question? I mean, it would even work during the day.

-Peter

Doesn't seem terribly practical.

[Vellmont]

So it only transmits 2 km, and presumably someone has to be looking in the right direction to receive your signal, and you need some kind of special equipment to encode a long message. This just looks like the wrong approach. It seems to me there's always a trade-off between distance, information transmitted, and signal power (a rough restating of Shannon/Hartley). I don't know how far flares can be seen, but that's already a chemical means of sending a short message a limited distance.

One thing that might be interesting, the ability to produce a powerful radio signal by some chemical means. You wouldn't be able to transmit much information beyond say "help!", but if you had a satellite in geo-stationary orbit looking for these signals (and somehow triangulating the position) that might solve the "has to be someone looking" problem. Whether there are chemical reactions that produce radio signals, I have no idea.

Re:hand cranked flashlight

[mikael]

I guess if they have a airman down in hostile territory with the enemy having access to frequency monitoring equipment, how does the person transmit his coordinates without broadcasting anything.

Reminds me of those experiments that we used to to do in cub scouts - sticking a small mirror onto a thin sheet of clingfilm and watching how sound waves changed the direction of reflected light - to demonstrate how sound was just air moving rapidly.