Biomimetic chromatophores for camouflage and soft active surfaces

Abstract

Chromatophores are the pigment-containing cells in the skins of animals such as fish and cephalopods which have chromomorphic (colour-changing) and controllable goniochromic (iridescent-changing) properties. These animals control the optical properties of their skins for camouflage and, it is speculated, for communication. The ability to replicate these properties in soft artificial skin structures opens up new possibilities for active camouflage, thermal regulation and active photovoltaics. This paper presents the design and implementation of soft and compliant artificial chromatophores based on the cutaneous chromatophores in fish and cephalopods. We demonstrate artificial chromatophores that are actuated by electroactive polymer artificial muscles, mimicking the radially orientated muscles found in natural chromatophores. It is shown how bio-inspired chromomorphism may be achieved using both areal expansion of dielectric elastomer structures and by the hydrostatic translocation of pigmented fluid into an artificial dermal melanophore.

25th Anniversary Article: A Soft Future: From Robots and Sensor Skin to Energy Harvesters

“…When combined with different actuation schemes, such adjustable colours open applications in the camouflage of soft machines. Alternative routes are in the further development of devices based on microfluidics, which may also be combined with dielectric elastomer actuators 47. Smart glass and windows with tunable colours may be an immediate application of such technologies.…”

Biological versus electronic adaptive coloration: how can one inform the other?

“…The iridophores are not the only component of the cephalopod that humans have taken inspiration from. Recently, a group at the University of Bristol used inspiration from the underlying mechanisms of chromatophore actuation to create artificial elastomeric chromatophores that undergo optical modulation in response to electrical stimuli [67]. In addition, a simple soft machine constructed from polymers was equipped with microfluidics to change the color and pattern of the small robot; this work was inspired by cephalopods and other animals with adaptive coloration [68].…”

Masters of disguise

“…By hydraulic pumping of the fluid, the opacity of the ink cell can be reversibly switched from completely transparent to completely opaque. ' 4 They had achieved a monochromatic colour change and provided a potential means of creating an artificial camouflage skin.…”