As the largest “organ” of the human body, the skin is a major interface in our interactions with the world around us. Skin contains specialized chemical, mechanical, and temperature biosensors that are critical for detecting harmful stimuli. Although the skin excels at repairing itself when damaged, acute injuries can permanently eliminate some or all of its sensory capabilities over the affected area, creating a “blind spot.”
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Because current skin repair therapies cannot restore such losses of sensitivity, some researchers have turned to artificial skin as a viable alternative. Flexible artificial skin can accommodate bio-compatible electronic devices and sensors to imitate the natural functions of human skin. However, one crippling limitation of such wearable electronics is that they require an external energy source, like batteries.
In a recent study led by Professor Joondong Kim of Incheon National University, Korea, a research team developed an innovative type of artificial skin containing a self-powered temperature sensing platform. Their biosensing device addresses the key limitations of previous approaches and offers realistic temperature sensing capabilities by mimicking the way human skin reacts to extreme stimuli. Their paper was made available online on November 8, 2021, and will be published in Volume 91 of Nano Energy in January of 2022.
The proposed artificial skin was produced using flexible and transparent thin layers of zinc oxide (ZnO), nickel oxide (NiO), and silver nanowires that, together, form a photovoltaic device. In other words, this artificial skin converts ultraviolet light into useful electricity, which can be used to power wearable electronics in a straightforward and sustainable way.
The temperature sensing capabilities of the proposed artificial skin come from the use of ZnO, which generates an electrical current that increases with temperature (pyrocurrent). What’s remarkable is that this sensing platform has inherent memory properties, meaning that the pyrocurrent is more or less amplified depending on previous exposure to extreme temperatures. In a way, this mimics some of the sensory memory mechanisms that human skin has and on which our body relies to keep away from harmful stimuli. “Artificial skin could become an immediate solution for people with damaged skin sensors so that they can once again experience the natural environment around them with ease,” explains Prof. Kim.