MedicalResearch.com Interview with: Dr. Ming Yang Key Laboratory of Microsystems and Microstructures Manufacturing, Harbin Institute of Technology, Harbin, China  MedicalResearch.com: What is the background for this study? What are the main findings? Response: Self-healing materials and coatings are smart solutions to environmental and energy problems. There are heavy demands for these materials in many productions such as consumer electronics, the automotive industry and healthcare. Current coatings that can self-heal are typically soft. This means they are not as anti-scratch as rigid surfaces and the benefit of the ability to repair themselves could be overwhelmed by their limited robustness vulnerable to normal mechanical contact. It would be very useful to have a self-healing coating with a hardness that can be comparable or even outperform rigid coatings. This is normally difficult because mechanical hardness and self-healing are two conflicting properties with the opposite dependence on polymer dynamics. One good example in this context is many soft tissues can self-heal, but a notable exception is tooth enamel, which is the hardest part in our body but has no way to recover after decay. A new design will be needed to circumvent the fundamental limitation. We find that by mimicking the structure of epidermis, it is possible to combine two contradictory properties into an artificial coating, namely, self-healing ability and high hardness. The success relies on the placement of a hard layer containing graphene oxide on top of a soft sublayer with a seamless interface for interlayer diffusion. This allows a similar healing mechanism as that in skin, but the coating is not soft and has a hardness that even approaches tooth enamel.