Self-healing polymer ‘skin’ developed
A synthetic material has been developed by scientists at Stanford University that is capable of repeatedly healing itself. It is hoped that the material will pave the way for improved prosthetics as well as electronic equipment that is able to self-repair.
The material will heal if torn or cut but is also sensitive to very slight pressure. It was developed to emulate the properties of human skin as closely as possible. The team responsible for developing it was led by Professor Zhenan Bao.
Previously, self-healing materials suffered from drawbacks such as high temperature requirements or only being capable of repairing themselves once. The team worked to avoid these flaws while also producing a material that could conduct electricity so that the range of its potential applications is hugely increased.
The material was initially developed by creating a polymer consisting of long chains of molecules joined by hydrogen bonds. The molecules are easily broken apart due to the weak attraction between the hydrogen atoms but they also reconnect, restoring the original structure. The polymer was then strengthened through the addition of nickel particles, which also contributed to the conductivity of the material.
If cut, the material regains 75% of its original strength after just a few seconds, and regains almost 100% of its strength after 30 minutes. In an experiment, a section of material that was made to repair 50 times retained the same strength characteristics of an undamaged sample. The presence of the nickel particles affects the absolute efficiency of this material, however, and further research is being done to make them interfere with the healing process as little as possible.
One reason for doing so is that the nickel particles are key to the material’s use as a sensor, or being able to ‘feel’ if used in prosthetics. Pressure causes the space between nickel particles to change, affecting the resistance. In turn, this can be translated into information about both the pressure and tension the material is being subjected to.
Further work is being done to make the material stretchable and transparent so that it can be used for wrapping and overlaying electronic devices or display screens.