Their work appeared May 5 in the journal Advanced Materials.
“This stretchable electronic fabric we developed has many practical uses,” said Michael McAlpine, a University of Minnesota mechanical engineering associate professor and lead researcher on the study, in a U of M news release.
“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,” McAlpine said.
McAlpine – first at Princeton University and then at the University of Minnesota after 2014 – has pioneered the creation of custom 3D printers able to do far more than what is available on the market. While at Princeton, he garnered attention for 3-D printing an ear out of living cells, while printing an antenna inside the ear at the same time.
Creating the stretchable sensors required the building of a one-of-a-kind multifunctional 3D printer, with 4 nozzles to print the “inks” making up the sensory devices layers. There’s a silicone base layer, conducting ink for top and bottom electrodes, and a pressure sensor shaped like a coil. There’s also a sacrificial layer holding the top layer in place while it sets; the final manufacturing process includes washing away the sacrificial layer.
The sensors stretch up to 3 times their original size. Even better, all the inks set at room temperature, versus the hot plastic inks used in conventional 3D printers.
“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.”
McAlpine next wants to experiment printing on a real body, as well as trying semiconducting inks.
“The possibilities for the future are endless,” McAlpine said.
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