This article was taken from the September 2013 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
How can farmers save water when watering crops? With sensors printed on paper and powered by radio waves in the air. SenSprout, developed by Yoshihiro Kawahara from the University of Tokyo, gives real-time measures of soil moisture to make irrigation more efficient.
Working with engineers at Georgia Tech and MIT Media Lab, Kawahara aimed to create an affordable device, so he made it out of paper. "We found a method to print an electronic circuit on to paper using silver nanoparticles," he explains. Using commercially available ink that contains 20-nanometre-long silver particles, they printed the sensors and antenna directly on to the node. The antenna harvests ambient energy by converting radio waves from local broadcast towers into DC current.
Kawahara has shown that it's possible to print the circuits using an off-the-shelf inkjet printer, and thinks farmers will be able to download their own sensors in the future. "You can print a circuit and the user simply needs to fold the shape," he says. "Like origami."
This article was originally published by WIRED UK
