Researchers have succeeded in developing an electronic skin (e-skin) that should play an important role in the next generation of future applications such as personalized medicine, prosthetics, artificial intelligence and soft robotics
[Translation by Dr. Moshe Nachmani]
Material that mimics human skin? Tensibility, strength and sensitivity are properties that can be exploited to collect real-time biological data. Explains lead researcher Yanchen Cai, a postdoctoral student at King Abdullah University in Saudi Arabia (KAUST): "An ideal electronic skin should mimic the many natural functions of human skin, for example, sensing temperature and touch, accurately and in real time." However, the development of flexible electronic components capable of performing such delicate tasks, while standing firm in the difficulties and challenges that confront them in everyday life, is a challenging field, and in addition - every material involved must be suitable at the highest level.
Most types of electronic skins are obtained as a result of spreading a layer of active nanomaterial (the sensor) on a stretchable surface that is attached to human skin. However, the connection between these layers is usually weak, a fact that reduces the durability and sensitivity of the material; Alternatively, if the connection is too strong, the flexibility becomes limited, a fact that can cause chipping and breaking the circuit. "The field of electronic components that mimic skin activity continues to develop at a spectacular pace," says the lead researcher. "The development of two-dimensional sensors accelerated the efforts to convert these mechanically strong materials with one-atom thickness into functional and stable artificial skin."
"Hydrogels contain more than 70% water, a fact that makes them most suitable for the tissues of human skin"
The research team has now succeeded in developing a stable electronic skin using a hydrogel reinforced with silica nanoparticles as a strong and flexible substrate, in combination with two-dimensional titanium carbide (MXene, two-dimensional inorganic compounds, Wikipedia) as the sensing layer, bound together by means of nanowires with high electrical conductivity. "Hydrogels contain more than seventy percent of water, a fact that makes them the most suitable for the tissues of human skin," explains the researcher. By stretching the hydrogel in all directions, using a layer of nanowires, and then carefully controlling their release, the researchers created conductive pathways for the sensing layer that remained intact even after being stretched 28 times its original size.
Their electronic skin prototype is able to sense objects twenty centimeters away, respond to stimulation in less than a tenth of a second, and when used as a pressure sensor, can sense handwriting written on it. The skin continued to function properly even after 5000 times of deformation, returning to activity after about a quarter of a second each time. "It is an unprecedented achievement that electronic skin manages to maintain its stability even after being reused over and over again," said the researcher, "a finding that indicates an accurate imitation of the elasticity and rapid restoration of human skin."
Such an electronic skin will be able to monitor a range of biological information, for example - changes in blood pressure, which can be caused by fluctuations in the arteries, up to movements of limbs and large joints. This data can be shared and stored in the cloud through wireless networks.
"One of the bumps that still remain in terms of fast and efficient distribution of electronic skin is increasing the dimensions of the high-resolution sensors to realistic dimensions," said one of the researchers, "at the same time, XNUMXD printing with the help of a laser offers new possibilities in this field." "We anticipate that this technology will flourish beyond the field of biology alone," said the lead researcher. "Stretchable sensing surfaces will one day be able to monitor the structural integrity of inanimate objects, such as furniture and airplanes," adds the researcher.
