by Mohab Aly
Seeing the 'Low Battery' alert on your smartphone is enough to send anyone into a frenzy.
But a group of researchers have developed a solution that not only lets you power your own device, but allows you to share your charge with others in need - without using a power pack.
Called PowerShare, this technology consists of flexible coils and docking aids embedded in a smartphone or smartwatch to transfer power to devices just by touching them together.
A number of devices now exist to provide extra power to mobiles and wearables, but although external power packs have become popular, they add size and weight, and mobile hand generators and solar cells produce only limited amounts of power.
Developed by researchers at the University of Bristol, PowerShare is a circuit design based on the QI standard and uses a class E amplifier for a transmit circuit and a QI based receive circuit.
Once the technology is placed inside a smartwatch or smartphone, simply tap it with another device and watch it charge. The inventors estimate that around 12 seconds of charging would give users one minute of talk time and two minutes would generate enough power to watch four minutes of a video.
The average Wireless Power Transfer gadget consist of at least two coils, one located in the power transmitter and the other in the power receiver. As electricity moves through the power transmitter coil, it creates an electromagnetic field that sends a charge to the next coil. In order to recreate the magnetic shielding, they used ferrite plate and copper tape placed on the back of coils — this hindered transmitted energy from getting close to human tissue
One drawback of PowerShake is that twice as much energy needs to be transmitted as is received. "The power transfer is not ever going to be cost-free", "That's just the intrinsic power cost of wireless charging in general — wireless charging is always going to consume more power than wired charging."