Researchers have created an artificial skin that can ‘bruise’ upon impact similar to actual skin, helping reveal when a robot or prosthetic is potentially damaged. The fake bruises are intended to function as a type of warning sign that the artificial limb or structure may need to be evaluated to ensure it doesn’t continue to unintentionally strike an object.
Bruising as an alert
Artificial skin is a material that resembles actual skin; it is commonly used for prosthetics and increasingly with robots. The skin, depending on its design, may be equipped with sensors that provide a degree of sensing capabilities, such as the ability to detect when the limb is in contact with a surface.
Going forward, these artificial skin materials may also feature a ‘bruising’ function that results in discoloration where the surface strikes an object. Unlike a person who may, for example, hit their leg against a post, a robot can’t report when one of its limbs has been struck, potentially resulting in damage that could go undetected until it gets worse.
The bruisable artificial skin was developed by researchers in China and recently detailed by the American Chemical Society. The material works by detecting forces using ionic signals, making it a conductive hydrogel that exceeds many of the capabilities of electronic skins (“e-skins”), at least when it comes to factors like biocompatibility and stretchiness.
According to the paper detailing the artificial skin, the bruising function is made possible by using a molecule called spiropyran that transitions from a pale yellow to a blue-like color when subjected to mechanical stress. As with actual bruises, this discoloration slowly returns to its original color after several hours.
The skin you know
Testing performed with this ionic hydrogel material (“I-skin”) found that it behaves similar to human skin — it can be stretched, for example, without bruising, but will present the discoloration if subjected to potentially damaging force, such as when repeatedly smacked or aggressively pinched.
Though you won’t yet find this material in use with prosthetic devices and robots, the development paves the way for a life-like artificial skin that may one day behave similar to the real thing. It’s unclear whether the researchers plan to integrate sensing capabilities in the material that may enable robots to also detect when they’re touched.