Before purchasing a phone, we see if its battery can survive a long day without dying suddenly due to lack of charge. The battery has been an important concern for mobile makers as well, and they have been striving to enhance the battery’s efficiency so that it can run longer without having to be charged. But researchers from the University of Washington have gone as far as designing a cell phone that doesn’t require a battery at all!
The device is made up of off-the-shelf components printed on the circuit board and contains a microphone, a number pad (with capacitive touch buttons) and a headphone jack.
Though the looks and functions of this cell phone do not resemble those of a normal phone, it requires only a trivial amount of power of the order of a few microwatts. And this power is harvested by the phone itself, making use of the energy from radio signals and light that fall on it. Photodiodes on the device help convert light energy to electricity while an antenna is used to get power from radio signals.
In the process of making a call, regular phones go through a power consuming step- converting the analog speech signal into a digital form for the device to understand. This has been skipped in the battery-free phone. The vibrations that are developed in the speaker when a person speaks are made use of and an antenna connected to these components uses this motion to transmit the speech signal. The team designed a custom base station to transmit and receive the RF signals.
The team of researchers from the University of Washington
The team also demonstrated Skype calls using the device. To speak, one needs to press a button to activate the microphone and to listen to the speaker on the other side, headphones must be used. You can check out the video here.
The current range of base station is 31 feet and it can be improved to 50 feet with the help of a tiny solar cell. Currently, the team is focussing on improving the operating range, securing the conversations using encryption and including the option of video streaming.
Let’s hope this works and helps us get rid of the tedious work of charging our phones constantly!
Image sources: University of Washington, Wired.