Scientists have been exploring the field of soft robotics for use in healthcare systems. They aim to emulate the sense of touch. However, they have not had much success with tactile-sensing technology while fine-tuning dexterity.
In an experimental study, published in the Journal of the Royal Society Interface, scientists made a comparison of the performance of an artificial fingertip with that of neural recordings made from the human sense of touch. The study also describes an artificial biometric tactile sensor, the TacTip, which the scientists had created. According to the study, TacTip offers artificial analogs of the dynamics of the human skin and the nerves that pass information from skin receptors to the central nervous system. In simple words, TacTip is an artificial fingertip that mimics nerve signals on human fingertips.
The researchers created the artificial sense of touch. They used papillae mesh that they 3-D printed and placed on the underside of the compliant skin. This construction is similar to the dermal-epidermal interface on real skin and is backed by a mesh of dermal papillae and biometric intermediate ridges, along with inner pins that are tipped with markers.
They constructed the papillae on advanced 3-D printers. The printers mixed soft and hard materials, thereby emulating textures and effects found in real human fingertips. They actually reconstructed the complex internal structure of the human skin and the way it provides for the sense of touch in human hands.
The scientists described the effort as an exciting development in soft robotics. They claim that 3-D printing tactile skin would lead to more dexterous robots. They also claim that their efforts could significantly improve the performance of prosthetic hands by imbibing them with an in-built sense of touch.
The scientists produced artificial nerve signals from the 3-D printed tactile fingertips. These signals look very similar to the recordings from actual, tactile neurons. According to scientists, human fingers have several nerve endings known as mechanoreceptors that transmit signals through human tactile nerves. The mechanoreceptors can signal the shape and pressure of contact. Earlier, others had mapped electrical signals from these nerves. By comparing the output from their 3-D printed artificial fingertip, the scientists found a startlingly close match to the earlier neural data.
A cut-through section of the 3-D printed tactile skin shows a white plastic that forms the rigid mount for the flexible black rubber skin. Scientists made both parts on advanced 3-D printers. The inside of the skin has dermal papillae, just as the real human skin also has.
In comparing the artificial nerve recordings from the 3-D printed fingertip with the 40-year-old real recordings, the scientists were pleasantly surprised. The complex recordings had many dips and hills over ridges and edges, and the artificial tactile data also showed the same pattern.
However, the researchers feel that the artificial skin still needs more refinement, especially in the sensitivity area pertaining to fine detail. As such, the artificial skin is much thicker than the real skin is. Scientists are now exploring different means of printing 3-D skins that mimic the scale of human skin.
