Scavenged current gets a regular boost
The market for energy scavenged from the environment is buoyant at the moment due to the demand for self powered sensor clusters for Internet of Things applications. Sensors are being placed in areas where it would be hard to connect to the mains or replace batteries, so drawing energy from the environment is the logical solutions.
The simplest of these clusters will contain a sensor, a microcontroller and a wireless transmitter in addition to the energy scavenging technology, storage and regulation. At a set time, the microcontroller will wake, prompt the sensor for a reading and transmit the reading to the wireless hub. This template has become very popular and manufacturers have produced very low-powered components for these applications. But, some industries are either looking for more functionality, or for smaller solutions and that has posed a challenge to manufacturers. How do you supply enough current without a battery? What if the sensor cluster needs the energy to receive commands and control an output?
Now, researchers at the university of Alberta may have stumbled on a solution. One PhD student, Jun Liu, was using an atomic force microscope, which uses a cantilever type sensor to “feel” the object, in an unrelated experiment, when he noticed a current when there was meant to be no electricity applied. He decided to get to the bottom of the situation and found it was the friction between the probe and the material causing the current to flow. Liu likens the phenomenon to generating static electricity by rubbing a carpet, but in this case the electricity wasn’t a high voltage discharged at once like static electricity, it generated a constant, regular current.
The discovery could have huge ramifications for the power industry. Nanoscale generators could generate a constant current from almost any source, which would revolutionise the development of sensor clusters initially and the industry as a whole eventually. Sensors could be placed inside engines or other machinery and generate their own power from the vibrations, meaning the microcontroller could always be on and listening for instructions. Larger self-powered clusters may be developed with a much higher level of functionality than just wake, measure and send.
The paper by Liu and his fellow researchers at the University of Alberta was published in Nature Nanotechnology and can now be found online. It is called, “Direct-current triboelectricity generation by a sliding Schottky nanocontact on MoS2 multilayers” by Jun Liu, Ankur Goswami, Keren Jiang, Faheem Khan, Seokbeom Kim, Ryan McGee, Zhi Li, Zhiyu Hu, Jungchul Lee & Thomas Thundat.
