Researchers outfitted this robotic hand with the TacTip device on the pinky finger. (Image Credit: University of Bristol)
Bristol University researchers developed TacTip, a 3D-printed fingertip that provides the same sense of touch similar to human skin via artificial nerve signals. This artificial fingertip could eventually revolutionize the world of robotics and even improve prosthetic gripping capabilities.
According to Nathan Lepora, a professor from the University of Bristol's department of engineering mathematics, humans generate a sense of touch from complex structures inside the skin. The team set out to replicate that feature by 3D-printing a mesh of pin-like papillae similar to those located under human skin. As a result, the device can detect shapes before transmitting this data as artificial nerve signals. Their robotic fingertip is made of a rubber-like material and soft elastomeric gel. Placed inside a Stratasys-3D printed casing, TacTip acts like a sensor via its nodular pins and mesh of ridges implanted along the surface.
The device's structure contains pin tips with markers relying on lateral movement to detect skin deformations. That occurs before an array of tiny cameras collect and relay the data. The optical markers can gradually be tuned to match sensory stimuli that the human body distributes to the central nervous system and brain. This, in turn, mimics the sensation associated with feeling objects.
The researchers say this artificial fingertip could have prosthetic and factory machine applications. (Image Credit: University of Bristol)
"We found our 3D-printed tactile fingertip can produce artificial nerve signals that look like recordings from real, tactile neurons. Human tactile nerves transmit signals from various nerve endings called mechanoreceptors, which can signal the pressure and shape of a contact. Classic work by Phillips and Johnson in 1981 first plotted electrical recordings from these nerves to study 'tactile spatial resolution' using a set of standard ridged shapes used by psychologists. In our work, we tested our 3D-printed artificial fingertip as it 'felt' those same ridged shapes and discovered a startlingly close match to the neural data," said Professor Lepora.
The researchers performed three human touch experiments on TacTip, testing its force, shape, and orientation feedback. In the first experiment, which had the fingertip fitted on an ABB six-axis robotic arm, TacTip exhibited a human-like response to pressure with a quicker peak intensity.
TacTip is also less sensitive compared to natural skin when detecting the orientation of various gratings. The team says this may occur due to the artificial skin's thickness and less flexible quality. Apart from a minor sensitivity loss, the team suggests a high degree of convergence exists between both the device and natural skin.
With further development on this device, the team says they could attach it to a factory machine's robotic hands, providing sensory perception for grip adjustments when picking up objects. In this case, the machines can automate certain tasks requiring a human touch.
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