Graphene grains joined together like dots in a pointillist painting, could be as strong and impermeable as Superman’s scan.
Since its discovery in 2004, graphene has been demonstrated to possess an array of electronic, mechanical and optic properties that could have revolutionary effects on solar power utilization, medicine, astronomy, photography and other fields.
Science Recorder reports the results of a new study, published in Science, by Columbia Engineering researchers, who have determined that a mosaic of graphene made from small grains is nearly as strong as crystalline graphene. This contradicts previous findings regarding its composition.
Graphene consists of a layer of carbon in a lattice of hexagonal carbon atoms linked together one atom in thickness. In its crystalline form, grapheme is the strongest material yet discovered, and yet as thin as Saran Wrap. However, crystalline graphene is too rare for practical use.
Previous films of graphene using chemical vapor deposition (CVD) methods for post-processing, have involved growing single layers of graphene on copper substrates in furnaces at high temperatures. The grapheme layer that was removed from the copper indicated weaker boundaries between grains and was consequently weaker in structure. However, that was because the chemicals used to remove the graphene from the copper damaged the grapheme and severely degraded its strength.
In 2008 the Columbia group obtained flakes of graphene by applying exfoliation, or mechanical peeling, from a graphite crystal. But this is a time-consuming and impractical method that would not allow for many potential applications.
Applying the new CVD process to larger grains of grapheme, using a different type of echant, or corrosive element, maintained the perfection of the crystal lattice and prevented damage to the graphene. The grapheme thus produced was just as strong as the exfoliated graphene but researchers also found that small grains of graphene exposed to the new CVD process produced a layer that was 90% as strong as the crystalline form.
Large areas of graphene could be used for a wide variety of applications, such as flexible electronics and strengthening components, which means it could make television screens that roll up like a poster, or tough composites that could replace carbon fiber.
Extreme Tech reports a study by researchers in Japan and the U.S. that has found that graphene has a very sensitive thermoelectric response to light. When it is struck by light of almost any wavelength, it can produce an electric current. This effect is caused by a hot carrier response, in which the electrons gain enough energy to move, but the underlying lattice of carbon stays cool.
A hot carrier response has previously been observed only in materials that are reduced to nearly absolute zero by a powerful laser. Graphene’s hot carrier response occurs at room temperature and across a wide range of frequencies, and requires a very weak source of light for its effects to be triggered.
These properties make it ideal for camera sensors, photovoltaic cells, and fiber-optic communications.
Graphene is both as in enduring and sensitive as we imagine Superman’s skin to be.
ExtremeTech has reported a further discovery regarding the properties of graphene. Researchers in Singapore are reporting that they have created a graphene photodetector that is 800 times more sensitive than previous graphene photodetectors, and 1,000 times more sensitive to light than imaging sensors currently utilized in cameras,
This would allow cameras to make clear photographs in very dim light, says AZ.com. Such a new sensor could be employed in many imaging devices, such as infrared cameras, traffic speed cameras, satellite imaging and handheld digital cameras. A graphene sensor operates at a relatively low voltage, and requires a small amount of energy: 10 times less than current sensors. This could lead to an increase in the life of camera batteries.
Scientific American reports that graphene’s ability to absorb light over a broad range of wavelengths may allow it to be used in ultrashort laser pulses of any color. This could help researchers build smaller, less expensive, and more versatile ultrashort pulse lasers, with potential applications for micro-machinery and medicine.
UC Berkeley scientists, according to Mother Nature News, have created a gel made of graphene and a synthetic protein similar to elastin, which is found in humans’ blood vessels and skin. Graphene produces heat when exposed to infrared light, and the elastin responds to the heat induced by the light. Such a combination could be used to build complex octopus-shaped “soft” robots in the future.
Graphene could create layers that would be as impervious to bullets and bombs as is Superman’s skin.
By Tom Ukinski