3D printed fingertips look like human skin

Machines can beat the best chess player in the world, but they can’t handle a chess piece as well as a baby. This lack of robot dexterity is partly due to the fact that artificial grippers lack the fine tactile sense of the human fingertip, which is used to guide our hands when we pick up and manipulate objects.

Two articles published in the Royal Society Interface Journal provide the first in-depth comparison of an artificial fingertip with neural recordings of the human sense of touch. The research was led by Professor of Robotics and AI (Artificial Intelligence), Nathan Lepora, from the Department of Mathematics Engineering at the University of Bristol and based at the Bristol Robotics Laboratory.

“Our work helps uncover how the complex internal structure of human skin creates our human sense of touch. This is an exciting development in the field of soft robotics – being able to 3D print tactile skin could create more dexterous robots or dramatically improve the performance of prosthetic hands by giving them a built-in sense of touch.” , said Lepora.

Lepora and colleagues created the sense of touch in the artificial fingertip using a 3D-printed mesh of pin-shaped papillae on the underside of conformal skin, which mimic the dermal papillae found between the outer and inner epidermal layers of human tactile skin. Papillae are made on advanced 3D printers that can mix soft and hard materials to create complex structures like those found in biology.

“We discovered that our 3D-printed tactile fingertip can produce artificial nerve signals that resemble recordings from real tactile neurons. Human touch nerves transmit signals from various nerve endings called mechanoreceptors, which can signal the pressure and shape of a touch. Classic work by Phillips and Johnson in 1981 first plotted electrical recordings of these nerves to study “tactile spatial resolution” using a set of standard striate shapes used by psychologists. In our work, we tested our 3D-printed artificial fingertip as it ‘felt’ these same ridged shapes and found a surprisingly close match to neural data,” Lepora said.

“For me, the most exciting moment was when we looked at our artificial nerve recordings from the 3D printed fingertip and they looked like the real recordings from over 40 years ago! These recordings are very complex with hills and dips at edges and ridges, and we saw the same pattern in our artificial touch data,” Lepora said.

Although the research found a remarkably close match between the artificial fingertip and human nerve signals, it was not as sensitive to fine detail. Lepora suspects it’s because 3D-printed skin is thicker than real skin, and her team is now exploring how to 3D-print microscale structures of human skin.

“Our goal is to make artificial skin as good as or even better than real skin,” Lepora said.

– This press release was originally published on the University of Bristol website

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