US scientists have created a cell phone that promises to eliminate the need to always have a power outlet and charger nearby. The model, which does not require a battery, captures the energy required for its operation in the surroundings - from sources such as radio waves or ambient light. This amount of energy, compared to current models, is very small, but sufficient to power the device. To make low-power voice calls with minimal power, the key lies in how the device treats the signal.
When we make a phone call, our voice is captured in an analog format. In order for our device to understand the message and it reaches who we are talking to, that language must become digital. The change of format is that it allows the telephony towers to pick up the signal you are sending and pass it on to those on the other end of the line.
Instead of performing this conversion work, the new cell phone maintains the analog signal throughout the process. By recording the vibrations picked up by the microphone during the connection, the device forwards the signal to a transmission center created by the scientists. This is possible because of a technique called backscatter, which reflects the radio waves emitted by the central. Working via Skype, the novelty allows you to communicate with common devices, in addition to calling any number with a touch screen keyboard.
Its processing center also has an antenna capable of turning radio waves into useful energy, which will supply the device during the connection. In addition to the radio waves, the antenna also performed well using ambient light - captured with the help of a small solar cell (the size of a grain of rice). The technique ensures that the consumption is in the 3.5 microwatts - much smaller than the average 800 milliwatts that conventional cell phones usually spend to perform the same function.
Because it still does not work with conventional telephony towers, you need to stay close to the special antenna. The operating distance (10m with radio waves and 15m using light) is in fact still short, especially considering the mobility that cell phones usually offer. However, the researchers believe that the antenna may in the future come pre-wired to Wi-Fi routers, or even to conventional transmission towers.
Source: Super Interessante Magazine.