Waterloo University researchers have created sustainable smart devices that require no charging or batteries.
Part of the IoT arena, these battery-free objects could help lower maintenance costs and allow the devices to be placed in areas that are off the grid.
Professor Omid Abari, Postdoctoral Fellow Ju Wang and Professor Srinivasan Keshav were responsible for hacking radio frequency identification (RFID) tags and giving the devices the ability to sense their environment.
“It’s really easy to do,” said Wang. “First, you remove the plastic cover from the RFID tag, then cut out a small section of the tag’s antenna with scissors, then attach a sensor across the cut bits of the antenna to complete the circuit.”
In their stock form, RFID tags provide only identification and location. To give a tag eyes, the researchers hacked an RFID tag with a phototransistor, a tiny sensor that responds to different levels of light.
By exposing the phototransistor to light, it changed the characteristics of the RFID’s antenna, which in turn caused a change in the signal going to the reader.
The researchers then developed an algorithm on the reader side that monitors change in the tag’s signal, which is how it senses light levels.
Among the simplest of hacks is adding a switch to an RFID tag so it can act as a keypad that responds to touch.
“We see this as a good example of a complete software-hardware system for IoT devices,” Abari said. “We hacked simple hardware – we cut RFID tags and placed a sensor on them. Then we designed new algorithms and combined the software and hardware to enable new applications and capabilities.
“Our main contribution is showing how simple it is to hack an RFID tag to create an IoT device. It’s so easy a novice could do it.”
Image and content: University of Waterloo