Scientists in Hong Kong have developed artificial skin that bruises like the real thing. The material, called I-skin, could be used on artificial limbs to alert users they have damaged their prosthetics. It's embedded with a gel that turns from yellow to welt-like purple when subjected to physical stress. Volunteers wearing strips of I-skin on their fingers, hands and knees repeatedly banged the appendage against a wall, proving the'bruise' would appear if enough force was used. Scientists in Hong Kong have developed an artificial skin that will mimic the discoloration of a bruise if hit hard enough.

IMAGE: An artificial skin attached to a person's knee develops a purple "bruise " when hit forcefully against a metal cabinet. Credit: Adapted from ACS Applied Materials & Interfaces 2021, DOI: 10.1021/acsami.1c04911 When someone bumps their elbow against a wall, they not only feel pain but also might experience bruising. Robots and prosthetic limbs don't have these warning signs, which could lead to further injury. Now, researchers reporting in ACS Applied Materials & Interfaces have developed an artificial skin that senses force through ionic signals and also changes color from yellow to a bruise-like purple, providing a visual cue that damage has occurred.