“This stretchable electronic fabric we developed has many practical uses,” said Michael McAlpine, a University of Minnesota mechanical engineering associate professor. “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.”
Prof McAlpine says this type of wearable technology could eventually be used for health monitoring or by soldiers in the field to detect dangerous chemicals or explosives.
“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,” Prof 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.”
The team made the sensing fabric with a one-of-a kind 3D printer they built in the lab. The multifunctional printer has four nozzles to print the various specialised ‘inks’ that make up the layers of the device—a base layer of silicone, top and bottom electrodes made of a conducting ink, a coil-shaped pressure sensor, and a sacrificial layer that holds the top layer in place while it sets. The supporting sacrificial layer is later washed away in the final manufacturing process.
The inks used in these flexible sensors can set at room temperature, unlike conventional 3D printing using liquid plastics that are too hot and too rigid to use on the skin. The flexible 3D printed sensors can stretch up to three times their original size.
The researchers say the next step is to move toward semiconductor inks and printing on a real body.