Berkeley researchers create super responsive graphene earphones
Researchers at the University of California at Berkeley just invented the first ever set of graphene earphones. Graphene, which is a single layer of the purest carbon known, is also the thinnest and one of the strongest materials known to man.
The process by which the earpieces were constructed was discussed in the paper titled, “Electrostatic Graphene Loudspeaker” by Qin Zhou and A. Zettl dated March 10, 2013.
First isolated in 2004, graphene is being touted as the construction material of the 21st century. It is a two-dimensional material that consists of single ultra-thin layer of carbon atoms arranged in a honeycomb structure. While graphene is one of the thinnest materials known, it is also one of the strongest of materials. Graphene is able to conduct electricity as well as silver and it far surpasses all other materials as a conductor of heat, which includes diamond. Another incredible feature of this material is that it is incredibly dense, yet is completely transparent.
Now researchers at Berkeley have just effectively demonstrated a new use for graphene in the form of speakers. The far superior strength and electrical conductivity of the graphene outperforms even the most advanced earpieces.
The earpieces are unique because the diaphragm in them is made from an ultra-thin layer (30nm-thick), 7mm wide sheet of graphene. They then took the diaphragm and fitted it between a top and bottom layer of electrodes made of silicon coated with a thin layer of silicon dioxide.
The graphene headphones work much in the same way that a normal paper or rubber diaphragm speaker works. When the electricity is applied it in turns creates an electro-static force enabling the diaphragm then vibrates. When the oscillation is changed it creates a new frequency of sound generated from the vibrations in the airwaves.
Graphene speakers may work the same way as common speakers, but they have found that the clarity is far superior and has incredible performance capabilities with a very wide range and frequency response. Furthermore, the researchers said that with graphene speakers there is no need to add any padding, which is put in place to avoid unwanted frequency responses. In the March 10, 2013 paper, Qin Zhou who led the research writes,
An alternative approach to response spectrum broadening is to reduce both the mass and spring constant of the diaphragm so that inherent air damping dominates and flattens the response peaks. Moreover, with ambient air serving as the dominant damping mechanism, most input energy is converted to a sound wave, which makes such speakers highly power efficient. For these reasons (more detailed analysis is provided in the Supporting Information), the ideal audio transduction diaphragm should have small mass and a soft spring constant, and be non-perforated to efficiently displace the surrounding air.
The Berkeley researchers are predicting that graphene might possibly be the material of choice in future speakers in laptops and smartphones not only for their wonderful sound output but also because of their energy conductivity abilities. They also have demonstrated how it can be mass-produced easier with new vapor techniques that could create much larger diaphragms.
Image Source: Cornell University Library, arXiv: 1303.2391 – “Electrostatic Graphene Loudspeaker” by Qin Zhou, A. Zettl