Researchers at the Bristol Robotics Laboratory have developed a 3D-printed fingertip that creates signals similar to brain activity associated with human touch.
Replicating fine tactile senses is one of the greatest challenges of robotics, with artificial grippers and prosthetics generally failing to replicate humans’ delicate motor skills.
Led by Professor Nathan Lepora, the latest breakthrough saw the BRL team create a 3D-printed mesh of pin-like papillae on the underside of an artificial skin, which mimicked the dermal papillae found between the outer epidermal and inner dermal. layers of human tactile skin.
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Manufactured using advanced 3D printers that mix soft and hard materials to create biomimetic structures, these artificial papillae produce digital signals analogous to the neural signals humans exhibit when touching objects and entering into tactile spatial relationships.
“We found that our 3D-printed tactile fingertip can produce artificial nerve signals that look like recordings from real, tactile neurons,” said Lepora, a professor in Bristol’s Department of Engineering Maths and located at BRL† “Those shots are very complex with hills and valleys over edges and ridges, and we saw the same pattern in our artificial tactile data.
“Human tactile nerves transmit signals from several nerve endings called mechanoreceptors that can signal the pressure and shape of a contact. Classic work by Phillips and Johnson in 1981 first made electrical recordings of these nerves to study ‘tactile spatial resolution’.” “using a range of standard ribbed shapes used by psychologists. In our work, we tested our 3D-printed artificial fingertip because it ‘felt’ the same ribbed shapes and found a surprisingly good match to the neural data.”
Although the historical tactile data matched closely, the artificial skin did not exhibit the same level of sensitivity as human touch. According to Professor Lepora, this is probably because the 3D-printed skin is thicker than the real skin. His team at BRL is now investigating how to 3D print microscopic structures of human skin, with the work having far-reaching implications for areas such as soft robotics and prosthetics.
“Our work is helping to discover how the complex internal structure of human skin creates our human sense of touch,” says Prof. Lepora. “This is an exciting development in soft robotics – being able to 3D print the tactile skin can create robots that are more dexterous or significantly improve the performance of prosthetic hands by giving them a built-in sense of touch.
“Our goal is to make artificial skin as good – if not better – than real skin.”