Researchers have developed an electronic sensor that can measure pressure and temperature and transmit them to the brain. This could enable skin prostheses to feel.
Pressure, temperature, movement – the human sense of touch covers a wide range of sensations. researchers from the Stanford University has now succeeded in electronically replicating the complex system of stimulus and reaction of the human skin. Your so-called e-skin could in future give people with skin damage or amputations their sense of touch back.
That’s how people feel
The skin is the largest human organ. In principle, it is a large, stretchable sensor: it registers stimuli on its surface and transmits them in the form of nerve impulses to the central nervous system, which consists of the brain and spinal cord.
There, the stimulus is processed directly into a reaction that is finally carried out by the muscles. A simple example of this process is our muscle reflexes: If you touch a hot stove, you automatically pull your hand away.
Electronic skin requirements
Achieving these short reaction times with the help of an artificial system is just one of the challenges facing medical technology. Because the artificial skin has to imitate the mechanical properties of human skin: it should be soft, stretchy and thin.
It also has to withstand the stresses of everyday life, for example it shouldn’t tear directly and it should be waterproof. For the safety of its wearer, the electronic skin should also be operated with a low voltage. This also saves energy.
E-skin communicates with the brain
The aim is to integrate the electronic skin into the process of stimulus and reaction in the human nervous system. This process begins with an external stimulus that the e-skin registers with an electronic sensor. Pressure and vibrations are perceived via tiny pyramid-shaped highlights on the sensor. In addition, the electronic skin is equipped with a temperature sensor.
The registered stimulus is then translated via a circuit to the nervous system in such a way that it can perceive the signal as if it were a natural stimulus. The nervous system then processes this stimulus into a reaction – just like in the process with human skin.
In order to carry out the reaction – for example, to trigger a reflex – the reaction signal must then be translated back to the muscles. For this purpose, the researchers have also developed an artificial synapse.
First successes in tests on rats
This transmission of stimuli has already been successfully tested in rats. To do this, the researchers linked the electronic skin to the area of the brain that processes certain tactile perceptions. There, the simulated skin sensation was processed and passed on to the artificial synapse.
The result: the artificial stimuli triggered twitching in the rats’ legs. It is noteworthy that the stronger the simulated pressure, the greater the twitching. The animals are therefore able to perceive the intensity of the stimulus through the electronic skin and to react accordingly. Skin irritations were not found on the rats. In addition, the structure of the artificial skin enables it to function at low voltages of less than five volts.
Is the e-skin revolutionizing medical technology?
The e-skin was still only tested on rats. A lot can still be improved, for example the reaction time and an even finer gradation of the sensory impressions. Nevertheless, the researchers see their work as making a crucial contribution to the next generation of skin prostheses. And one day the electronic skin should also be used in robotics.