Imagine a robot changing its colours according to its surroundings in an absurd sequence of events, just like a chameleon. Better yet, imagine seeing a chameleon, but it is, in fact, a robot.
Developing an artificial camouflage at the level of a whole device is one of the most challenging tasks for researchers. But, a team of South Korean researchers have paved the way for a new artificial camouflage technology.
Chameleons can adapt and change their skin colour to blend with the background because of their iridophores, a particular layer of cells under the skin. Researchers Hyeonseok Kim, Joonhwa Choi, Kyun Kyu Kim, Phillip Won, Sukjoon Hong & Seung Hwan Ko have imitated this nature to create a robot chameleon capable of changing its colours.
Modelling Technique
Artificial camouflage is the functional mimicry of natural camouflage that can be observed in a wide range of species. The researchers stepped away from traditional microfluidic devices to take a fully electric approach.
In the model, the robot uses colour sensors, silver nanowire-made tiny heaters and thermochromic materials that change colour on exposure to different temperatures, using thermochromic liquid crystal ink. The robot has colour sensors underneath and a range of pre-programmed patterns that help it blend in.
According to Seung Hwan Ko, a thermal engineering professor and one of the authors, getting the colour transition up to nature’s speed was the most challenging. So, they used nanowire heaters to solve it. These machines heat up very fast, warm the artificial skin quickly and thus, it can change colour at the same speed as a chameleon. The team tested this on various high-resolution skin patterns to conclude that the robot could transition between different colours quite instantly.
The Ag NW heater was used to develop the team’s TLC based artificial camouflage device. This allowed the model to manipulate the temperature accurately and express the fine patterns on it. The group proposed a multi-layered Artificial Chameleon Skin consisting of a TLC ink layer and a Silver Nanowire heater. “All fabrication processes consist of repeated procedures: polymer annealing, fabrication of patterned silver nanowire heaters on each layer, and silver nanoparticle electrodes for the electrical connection between the layers,” according to the paper published by Nature.
Multi-layered Artificial Chameleon Skin design
The team uses a microcontroller to determine the target colour based on the brightness and dominance of red, green, and blue lights. Then, a colour sensor measures these through a serial communication protocol, Inter-Integrated Circuit.
The team had difficulty deciding whether to model the robot on a vertebrate or an invertebrate like an octopus or a squid. They chose an invertebrate model since it would allow for more freedom of movement. Chameleon’s simple body form was presented to suit the appropriate design and material structures for the team. They were able to shape the nanowires into dots, lines and scales to create a spot-on replica of the creature.
Future applications of this model can be used in transportation, beauty, and fashion, including cars that adapt their colours to stand out and even colour-changing cloth. According to the researchers, the chameleon surface is just another type of display; it can be made softer, stretchable or flexible, given the need.
Similar Researches
Aaron Fishman, a materials scientist at the University of Bristol and his team have designed a system that mimics how cephalopod skin works. The model’s design involves soft and elastic materials that are transformed into muscles that can rapidly change in size and shape in response to electrical signals. According to the researchers, this technology can be used in soft robots covered in stretchy silicone skin.
Another research, led by James Pikul of the University of Pennsylvania and Robert Shepherd of Cornell University, was inspired by octopus, cuttlefish’s papillae, or 3D bumps. The creature can inflate using muscle units for camouflaging. The team has created a synthetic version of cephalopod skin that can change from a flat, two-dimensional surface to a three-dimensional surface with bumps and pits. The researchers claimed that this ‘morphable skin’ could be used in furniture worn by robots for camouflage or entertainment where participants can feel these surroundings in a VR experience.
The US army is looking into a new “smart” camouflage mimicking cephalopod’s ability to change its skin colour and patterns instantly. The model will apply to the army owing to the creature’s ability to match their surroundings to warn off attackers. The creature’s skin consists of 18-30 muscle fibres that change the amount of pigment exposed. It also has a static infrared reflecting space blanked on its skin. Inspired by this, the researchers’ plan consists of infrared camouflage coatings and invisibility covering. They can also regulate the body temperature by varying the mechanical strain on the fabric.
However, these technologies are still in the initial stages and seeing their applications in everyday life is still in the coming future.
