Touchy subject: 3D-printed fingertip “feels” like human skin

Machines can beat the world’s best chess players, but they cannot handle a chess piece as well as an infant. This lack of robot dexterity is partly because artificial grippers lack the fine tactile sense of the human fingertip, which is used to guide our hands as we pick up and handle objects.

But now, scientists have created this sense of touch in an artificial fingertip using a 3D-printed mesh of pin-like papillae (bumps) on the underside of synthetic skin. These papillae mimic the dermal papillae found between the outer epidermal and inner dermal layers of human tactile skin.

This 3D-printed tactile fingertip can produce artificial nerve signals that look like recordings from real, tactile neurons.

The papillae are made on advanced 3D-printers that can mix soft and hard materials to create complicated structures like those found in biology.

“Human tactile nerves transmit signals from various nerve endings called mechanoreceptors, which can signal the pressure and shape of a contact,” explains senior author Nathan Lepora, professor of Robotics & AI (Artificial Intelligence) from the University of Bristol’s Department of Engineering Maths, UK.

Electrical recordings from these nerves were first plotted in 1981 to study “tactile spatial resolution” using a set of standard ridged shapes used by psychologists. In this work, researchers tested their 3D-printed artificial fingertip as it “felt” those same ridged shapes and discovered a startlingly close match to the neural data.

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

The research was published in the Journal of the Royal Society Interface.