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Camouflage can protect military personnel and equipment from observation by enemy forces. A material that can change color on demand could lead to an entirely new type of military camouflage. Inspired by the color-changing skin of cuttlefish and octopuses, Rutgers University engineers have created a 3D-printed smart gel that changes shape when exposed to light. The gel becomes an “artificial muscle” that can respond to changes in light by contracting, and may lead to new military camouflage, soft robotics and flexible displays.

The team also developed a 3D-printed stretchy material that can reveal colors when light changes. Their invention is modeled after the amazing ability of cephalopods such as cuttlefish, octopuses and squids to change the color and texture of their soft skin for camouflage and communication. This is achieved by the thousands of color-changing cells, called chromatophores, in their skin.

The research supports a new engineering approach featuring camouflage that can be added to soft materials and create flexible, colorful displays.

The researchers developed a 3D printable hydrogel, or smart gel, that senses light and changes shape as a result. Hydrogels, which keep their shape and stay solid despite containing water, are found in the human body, Jell-O, diapers and contact lenses, among many examples.

They incorporated a light-sensing nanomaterial in the hydrogel, enabling it to contract in response to changes in light. The light-sensing smart gel, combined with the 3D-printed stretchy material, changes color, resulting in a camouflage effect.

Next steps include improving the technology’s sensitivity, response time, scalability, packaging and durability, according to

The study was published in the journal ACS Applied Materials & Interfaces.