Prosthetics have been around since ancient times. The earliest evidence of prosthetic material is used by a 3000-year-old Egyptian mummy who wore a prosthetic toe made from wood and leather. Even Roman soldiers used wood and iron to fashion artificial limbs.
In our modern times, prosthetics are made more comfortable and more efficient, but most of them are still far from the natural features of the human body. However, users of prosthetics experience setbacks while learning to use the device. One of the major reasons why people prefer not to use prosthetics is the lack of sensory feedback, which frustrates the user.
Simulating Human Skin with Sensors
New technological advancements have made it possible to produce artificial skin that can mimic a person's sense of touch. At Stanford University in California, a group of researchers led by chemical engineer Zhenan Bao created the electronic skin or 'e-skin.' The team's goal has been to develop a prosthetic skin that is not only soft and flexible but also can transmit electrical signals to a person's brain and allow the user to sense pressure and temperature.
In their latest work, they were finally able to develop a thin sensor that can send a signal to the motor cortex of a rat's brain and cause the animal to respond when the electronic skin is pressed or squeezed. The motor cortex is the area of the brain that controls voluntary movements. The rats jerked their legs in response to various levels of pressure recorded by the brain, which depended on the strength of stimulation frequency. This response shows that the electronic skin effectively detects different pressure levels in the same way that humans and animals ordinarily do.
The electronic skin is thin and stretchable like regular human skin, sticking to surfaces like Band-Aid. Using sensors, external temperature and pressure are measured and sent to an implanted electrode towards the brain as electrical signals. These signals differ in terms of frequency to guide the brain in distinguishing between sensations such as soft touch and a firm handshake, a strawberry and an apple, and hot and cold objects.
Previous forms of electronic skin use soft sensors to sense touch, but they depend on fixed external factors in converting touch into electronic signals that can be measured. This method limits people from moving naturally. This challenge is finally addressed since the new electronic skin is entirely soft.
This innovation can lead to prosthetic limb covering development that can simulate how human skin senses things. As a result, the user can easily interact with their surroundings. The researchers hope this will apply to prosthetics and help create robots with human-like sensations.
How Does the Sense of Touch Work?
Just like the other senses, the sense of touch allows a person to collect information about the surroundings. What makes it different, however, is the fact that direct contact with the skin is needed to carry out this process.
The human skin contains many receptors that provide the means to feel things a person touches. These receptors include thermoreceptors, nociceptors, and mechanoreceptors. They are found at the top layers of the skin, called dermis and epidermis. The information gathered from the environment is changed into a signal the nervous system interprets.
RELATED ARTICLE: Fabricated Electronic Skin Perceive Pain Like Humans, Paving Way for Prosthetics and Robotics
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