Researchers at California Institute of Technology are working on how to upgrade mobile devices using microscopic chips that have better signal and bandwidth control.

The team, led by Chiara Daraio, a professor of mechanical engineering at Caltech, worked on phononic devices that have better functionalities than components used in today's mobile devices.

Nanometric Chips

The phononic devices vibrate at an extremely rapid rate of about tens of millions of times per second. It is made of silicon nitride drums that are 90 nanometers thick or approximately 1,000 times thicker than a hair strand. These drums are arranged in grids, each having different properties.

Arrays of these drums can be used as chips that serve as signal filters of various frequencies. Caltech postgraduate scholar Jinwoong Cha said that phononic devices can transmit one-way signals at high frequencies with reduced interference.

"In the future, these systems can be employed for stable ultrasound and radio frequency signal processing," the researchers wrote in their paper published in the journal Nature.

Manipulating Waves

In January, Daraio and her team of engineers at Caltech partnered with postgraduate scholars at ETH Zurich in Switzerland to systematically design metamaterials for specific use.

By altering a metamaterial on a microscopic level, they are able to redirect sound waves to soundproof a room or manipulate silicon to achieve lens-like focus.

Daraio said that prior to their work, there was no universal systematic way of designing metamaterials to control mechanical waves for various applications.

"Instead, people often optimized a design to fulfill a specific purpose, or tried out new designs based on something they saw in nature, and then studied what properties would arise from repeated patterns," she said.

According to Daraio, the manipulation of metamaterials is not only by changing its geometry but also by understanding how the structures connect and react on other surrounding structures. Researchers noted that the process is complicated, but they can use its predictability to design purpose-driven systems.

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