3D Printed ‘Skin’ Could Finally Give Robots a Sense of Touch

We could normally take heart that robots would never become too human like for comfort. Sure, they could look like us. They could talk like us. They can even be programmed to think like us. However, these bots couldn’t technically feel anything with the same sense of touch we humans have. Thanks to one group of researchers, that could all change. A team of engineers at the University of Minnesota developed a 3D printed stretchable “skin.” The fabric would be embedded with electronic sensors splayed out similar to our nervous system.

The researchers created a one-of-a-kind printer. It has four nozzles each with its own “ink.” These inks layer up into the electrode parts. The base consists of silicone. The top and bottom electrodes have a conductive ink. There’s also a coil-shaped pressure sensor and an extra layer to hold everything in place. This extra layer — dubbed the ‘sacrificial layer’ — washes away during the final stages of manufacturing.

These ink layers can all set at room temperature. No heat or immediate cold needed. Regular additive manufacturing practices take a while to cool. The liquid plastic is very hot and sets up too rigid to use on human skin. However, these 3D printed sensors are perfect for bionic skin. They can stretch up to three times their original size and return to an unstretched state with ease. This property allows the 3D printed inks to carve out its own niche in 3D printing research.

“This stretchable electronic fabric we developed has many practical uses,” said associate professor of mechanical engineering Michael McAlpine. McAlpine served as lead researcher for the University of Minnesota study. “Putting this type of ‘bionic skin’ on surgical robots would give surgeons the ability to actually feel during minimally invasive surgeries, which would make surgery easier instead of just using cameras like they do now. These sensors could also make it easier for other robots to walk and interact with their environment.”

[Image Source: College of Science and Engineering, UMN via YouTube]

The team assures everyone that the ultimate goal isn’t to print this bionic skin for robots. It’s in order to help humanity instead.

“While we haven’t printed on human skin yet, we were able to print on the curved surface of a model hand using our technique,” McAlpine said. “We also interfaced a printed device with the skin and were surprised that the device was so sensitive that it could detect your pulse in real time.”
He also said the best part of the innovation comes from its manufacturing.

“With most research, you discover something and then it needs to be scaled up,” the professor said. “This time, the manufacturing is built right into the process so it’s ready to go now.”
The study noted that “the custom 3D printing of functional materials and devices opens new routes for the biointegration of various sensors.” Next steps for the research team include creating semiconductive inks and ultimately printing on a human body.

The full research paper can be found on the Advanced Materials journal website.