Modern prostheses have long ceased to be pieces of metal, they are acquiring more and more functions inherent in real human limbs. The next step is the implementation of one of the most important and difficult options - the recreation of the sense of touch, when the owner of the prosthesis can feel his touch to something. Ideally, you can also control the pressure and perceive the feedback.
A group of American scientists has published developments on the creation of a prototype of artificial leather - or rather, a metamaterial with a touch control function. To do this, they took an elastic polymer and evenly deposited particles with a magnetic charge on its surface. A thin polymer membrane was wrapped around the magnetic pickup, but loosely to maintain a minimum gap. At rest, the particles did not come into contact with the sensor, but it was only necessary to slightly press on the membrane, to shift the material towards the sensor, as it worked.
The sensitivity of this metamaterial (the developers want to combine the sensor and the polymer membrane into a single whole) is amazing. The sensors reacted to falling water droplets, the movement of an ant's legs, a breath of wind, exactly as an applied force - the human skin perceives it differently. All that remains is to select the optimal configuration of the arrangement of magnetic particles, membrane thickness and sensor power in order to create artificial skin with the desired coefficient of touch.
But there is one big "but". Today, there is no effective way to transmit information from synthetic skin sensors directly to the brain, to the human nervous system. The microcontroller will easily select the necessary effort to pick up and not crush the fluffy kitten, but it is not yet able to convey the sensation of touching its fur.