In the quest to develop a reliable artificial skin sensor, engineers face three primary concerns–sensitivity and durability. Researchers at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia have developed an electronic skin that performs several natural skin functions without sustaining damage from daily activities.
Progress with artificial skin sensors currently suffers from an engineering paradox. Materials that mimic the flexibility of human skin offer high-sensitivity, but they don’t provide enough protection for the delicate electronic sensor components. Stronger, thicker materials can limit sensitivity, and although they offer more protection, they still may suffer damage from the thumps and bumps of everyday movement.
Seeking to create a strong, stretchable, highly sensitive e-skin, the KAUST team used silica nanoparticles to strengthen a polyacrylamide hydrogel, which is a flexible material that consists of more than 70% water. They developed an ultra-thin sensor layer using a potent carbon-metal compound known as 2D carbide MXene. After pre-stretching the hydrogel layer in all possible directions, they bound the two layers together with electroactive nanowires.
The resulting e-skin prototype maintained sensor integrity when stretched, even at 28 times its original size. It continued to function correctly even after enduring 5000 varying stretches, recovering within a quarter of a second each time. That level of recovery and accuracy mimics the properties of human skin. The prototype responds to external stimuli in less than 1/10th of a second, including objects up to 20 centimeters away. And it could sense pressure well enough to record words written by hand on its surface accurately.
A sensor this durable and accurate could monitor a variety of biometrics, including blood pressure, heart rate, limb and joint movement, and other real-time bioactivities. The research team hopes that their new prototype could one day have various applications, such as next-generation prosthetics, soft-robotics, and personal health monitoring. The researchers recently published a research paper about the e-skin in the journal Science Advances.