Artificial Chameleon Skin Promises New Developments In Wearable Tech

As scientists get better and better at making lightweight and flexible electronics, artificial electronic skin, aka. “e-skin”, is becoming increasingly viable. E-skins find application in a huge variety of industries including wearable tech, health monitoring, prosthetics, and smart robots by mimicking some of the key properties of the natural organ including flexibility and stretchability, pressure and temperature sensitivity, or the ability to self-heal. Now scientists have developed an artificial skin that actually surpasses natural human skin by incorporating the color changing capabilities of a chameleon.

Chameleon-inspired e-skin: incorporating three key components of real chameleon skin, this artificial alternative promises exciting new applications. Image adapted from Nature Comms. (2015) 6, 8011.Chameleon-inspired e-skin: incorporating three key components of real chameleon skin, this artificial alternative promises exciting new applications. Image adapted from Nature Comms. (2015) 6, 8011.

Human skin is a truly remarkable organ that we perhaps fail to appreciate due to its ubiquity. It is highly sensitive to changes in temperature, pressure and humidity. It’s water resistant. It’s flexible and stretchable. When injured, it is able to heal itself. And it does all this while consuming very little power. A true respect for these properties is firmly established, however, when one tries to develop a synthetic electronic skin. A flexible and stretchable network of electronic sensors that responds to a variety of stimuli with excellent spatial recognition, can be submerged in water and, perhaps most challengingly, can self-heal is a tremendous engineering challenge. Indeed, incorporating any one of these properties into an electronic device is a considerable feat. Aside from these base behaviors, certain animals possess skin that is even more advanced. Crocodile skin, for example, can detect environmental chemicals allowing them to choose the best possible habitat; and the skin of chameleons can change colors.

It is this latter creature that has inspired the latest research led by Professor Zhenan Bao of Stanford Univeristy’s Department of Chemical Engineering and published last month in Nature Communications. While not the first chameleon-inspired research, Bao and colleagues have developed for the very first time a material which possesses three of the key properties found in true chameleon skin: the ability to change colors, stretchability and pressure sensitivity. Not only that, the entire material can be processed in solution making fabrication simple, cost-effective, and easy to scale up for commercial applications – a frequent stumbling block for laboratory developments. The color-changing basis of the e-skin is an electrochromic polymer. Electrochromic materials, as suggested by their name, are those that can alter their color in response to an applied voltage. The researchers coupled this with a second polymer impregnated with carbon nanotubes such that it can change its voltage in response to pressure. The result? The e-skin changes from red to blue and back again with varying applied pressure. The team demonstrated the result adorably by putting the e-skin on a teddy bear and shaking its hand (really).

Teddy bear test case: shaking the bear's hand with differing pressures changed the color of his belt. Image reproduced from Nature Comms. (2015) 6, 8011.Teddy bear test case: shaking the bear's hand with differing pressures changed the color of his belt. Image reproduced from Nature Comms. (2015) 6, 8011.

The applications for such a development are myriad and range from purely decorative to medical or military in nature. For example, e-chameleon-skin can be integrated into smart devices, clothing and other wearables where it can easily allow the user to shift the device appearance in conjunction with their mood or style. Less superficially, it can be used for prosthetics or military robots where it could allow a camouflage function similar to that employed by chameleons themselves. No matter what the eventual use, the increasing ease with which scientists are able to imitate Mother Nature is sure to produce some exciting products in the coming years.

Via Phys.org and Nature Communications.