Sound Charging Your Phone? You Can with Piezoelectric Nanogenerators
Someday we may have the option to shout at our phones to charge them. As researchers at the Korea Advanced Institute of Science and Technology (KAIST) continue developing their technology to wirelessly charge phones 15 feet away, scientists from Nokia and Queen Mary University of London (QMUL) are attempting to make it commercially viable to charge smartphones and other electronic devices using sound. Korean researchers have already started pursuing the idea of speech or sound based charging some years ago by exploiting the piezoelectric effect. This time, the technology gets another boost in finally becoming usable for ordinary users of electronic devices.
Charging with Sound
Queen Mary University’s Joe Briscoe and Steve Dunn decided to undertake R&D work on sound-based battery charging as they studied how playing fast-tempo music stimulated and improved the ability of solar cells to convert sunlight into electrical power. This sparked their interest in developing a device that transforms motion energy into electricity.
In an interview with Mashable, Briscoe said that “charging by sound and vibrations could help improve the usability of electronic devices and allow them to work for longer, without worrying about connecting to a charger.” For him (and most likely for everybody else too), “it would also be helpful to the environment if we can use even a small amount of the waste energy in the environment.” There’s an abundance of ambient sounds in almost all places where people use their smartphones and other electronic devices. Harvesting these sounds and converting them to electricity is indeed an idea worth pursuing.
In the same interview with Mashable, Briscoe said that he believes charging phones using sound will be part of the future. He concedes, however, that there may not be enough energy in sound to completely supplant traditional charging (charging via AC power from wall outlets). Briscoe believes that this technology will most likely reduce the frequency of charging phones or other electronic devices.
Piezoelectricity and Nanorods
Sound charging is made possible through the use of piezoelectric materials. The concept of piezoelectricity has already been in existence for around two decades. As mentioned, Korean researchers have already started exploring the possibility of charging devices with sound. The researchers from Nokia and Queen Mary University, similarly, are working on the use of zinc oxide nanorods to generate electricity.
They developed a nanogenerator that works by exploiting the piezoelectric property of zinc oxide. Electricity is created when the zinc oxide nanorods are squashed, bent, stretch, or exposed to stimuli that physically rattle them. The verbs mentioned here (squash, bend, stretch) may sound like they require a considerable amount of energy to be achieved, that “sound does not sound” capable enough of doing them. Bear in mind, though, that the objects being squashed, bent, and stretched here are nanorods. They are very minute items that are even smaller than the human cell. As such, sound is definitely adequately capable of moving them in ways that will make them produce electricity.
The researchers created the zinc oxide nanorods by spraying a coating of liquid zinc oxide on a plastic sheet. This plastic sheet was later on placed in a mixture of chemicals and exposed to a 90°C temperature. The nanorods emerged after the heating process.
How Does Charging Work?
So how did the researchers harvest the electricity created when the nanorods stretched, bent, or squashed? Obviously, they couldn’t connect wires to the the nanorods individually. What they did was to use two sheets of aluminum foil (should have been gold but they wanted a more cost-effective option). The layer of nanorods was sandwiched in between the sheets of aluminum foil that served as the points for getting the positive and negative charges.
Needless emphasizing, there isn’t a commercially available device that uses the technology yet. However, the researchers have already built a prototype device, which is around the size of the Lumia 925 device from Nokia. This prototype is said to be capable of producing up to five volts of electricity by harnessing everyday ambient noise produced by traffic, music, chatter, and various other things and events. Most devices at present can already charge with 5 volts of power (the same voltage of USB power).
Without a doubt, this technology is certainly an advantage for all users. With all the noise everyone is exposed especially in cities, sound charging technology is definitely a welcome development. Here’s hoping for a faster commercialization of this technology. Also, device manufacturers should consider pouring in funds to make this technology available to everyone.