As part of my theorizing about ways to preserve information during a so called “Digital Dark Age,” I have spent a fair amount of time thinking about/looking for ways to imprint or encode messages without using electricity. You know, besides writing on paper, carving messages in stone, or micro-etching in metals. Realistically, we can use any type of medium to arrange patterns which communicate messages to each other and use any number of methods to contain and and release these messages. We are so wrapped up these days in sending all of our messages through electronically operated conduits (for good reasons – they’re really effective) that novel non-electrical means of communicating can take us by surprise.
David Walt of Tufts and George Whitesides of Harvard have developed self-powered “infofuses” which use chemical reactions to communicate. From what I can tell, you still need electricity to encode the fuses (they are currently using micropippeters and ink jet printers to encode them; and you need some kind of device to read the message. I still have a lot of questions about the process and its effectiveness in the field, but it’s an interesting approach at the very least.