Being our largest sensory organ, we receive a tremendous amount of information about our surroundings from our skin. Dense with somatosensors to detect external stimuli of pressure, temperature, and pain, skin proves very challenging to replace with an engineered substitute. As such, missing or damaged skin must typically be replaced by grafting — surgically removing skin from one part of the body, and transplanting it where needed. This process can be painful, prone to graft failure, and is limited in the amount of donor tissue that can be harvested.
In a recent advancement that may eventually allow artificial skin to produce sensory information akin to the real thing, Rahman, et al. have described an electronic skin that mimics three of the most prevalent and critical skin receptors — namely, the Pacinian corpuscle, thermoreceptor, and nociceptor. These receptors provide information about pressure, temperature, and pain, respectively.
The characteristic features of these receptors are very difficult to mimic with existing electronic sensor and data processing technologies, given the size constraints inherent in skin. However, with the results of another recent study that demonstrated a system that can convert the analog signal from artificial sensors into spikes in real neural networks, the researchers recognized the possibility now exists to construct a fully functional artificial sensory system. By using the sub-nanometer conductive filaments of memresistors to theoretically feed into biological neural networks, they devised tiny, flexible sensors that replace the primary sensory functions of skin.
The prototype device built by the researchers mimics the nearly-instant feedback response of biological somatosensors. According to the lead author “...some existing technologies have used electrical signals to mimic different levels of pain, these new devices can react to real mechanical pressure, temperature and pain, and deliver the right electronic response. It means our artificial skin knows the difference between gently touching a pin with your finger or accidentally stabbing yourself with it — a critical distinction that has never been achieved before electronically.”
There is still much work to be done before an artificial skin can fully replace the functionality of the real thing, but this research represents a major step in that direction.