UC Berkeley researchers invent invisibility cloak to conceal 3-D objects

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A team of UC Berkeley researchers published a study Thursday detailing a miniature invisibility cloak that can conceal 3-D objects by refracting light waves.

The cloak, made from a thin material covered with millions of gold-plated antennae, wraps around an object and uses the antennae to divert light waves from its surface, rendering it undetectable to the human eye.

Under the lead of Xiang Zhang, director of materials sciences at the Lawrence Berkeley National Laboratory and professor in the campus’s department of mechanical engineering, the team created the first model of the cloak six years ago. The previous design, however, presented limitations because it was made of a bulkier material and needed to have a fixed cylindrical shape.

“The old theory was not practical,” Zhang said. “If you wanted to cloak a person, you needed to carry a tank around you.”

Based on a completely different design principle, the current model of the cloak is extremely thin, measuring 80 nanometers thick, or one-thousandth the size of a single human hair. Tiny antennae act like a mirror to control the propagation of light to conceal the object underneath. The material itself is similar to a thin piece of cloth.

“This is probably closer to Harry Potter’s cloak,” Zhang said. “It’s like a T-shirt you can wear.”

While the experiment was capable of concealing a particle that was microscopic in size, researchers said it may be able to cloak larger objects as soon as five years from now. Currently, the thickness of the cloak is ideal, so researchers plan to expand the surface area of future models.

According to Zhang, there are many potential future applications of the technology. It could eliminate blind spots by making metal frames of cars transparent. Alternatively, the military may be able to use the technology to hide planes or tanks. Wrinkles and blemishes could be concealed with a design that would mold to the wearer’s features.

Jie Yao, an assistant professor in the campus’s department of materials science and engineering who did not participate in the study, believes it may be longer before the technology can be used by the public.

“Making such a material is very expensive,” Yao said. “If you really want to make a large object invisible, do you want to pay that price?”

For now, Zhang and his team are looking to make a fully functional invisibility cloak a reality. The next step is to apply the existing fabric technology on a larger scale, and according to Zhang, someone could make this happen in the not-too-distant future.

“Can you make a human size of the cloak?” Zhang said. “That’s the next question.”

Contact Cassandra Vogel at [email protected].