Flexible electronics seem to be a continually expanding area of electronics. However, a half-century of focus on silicon-based electronics has left the shelf set aside for materials that can be used for these new flexible electronics a bit bare.
Of late, there has been a big research push aimed at developing self-repairing, electrically conductive materials that can withstand the damage caused by the twisting and deformation of the materials. But thus far, most of that research has focused on self-repairing electrical conductors.
Now researchers at Penn State University have looked at developing a self-healing dielectric material. Dielectrics are just as important as conductors in that they provide electronic insulation and packaging.
“Most research into self-healable electronic materials has focused on electrical conductivity but dielectrics have been overlooked,” said Qing Wang, a professor at Penn State, in a press release. “We need conducting elements in circuits but we also need insulation and protection for microelectronics.”
In research described in the journal Advanced Functional Materials, the Penn State team developed a polymer nanocomposite that is strengthened with functionalized boron nitride nanosheets. The result is a material that, despite repeated flexion and torsion, is capable of recapturing all of its structural and electrical properties including mechanical strength, breakdown strength to protect against surges, electrical resistivity, thermal conductivity and insulation.
The self-healing works thusly: The boron nitride nanosheets connect to each other through hydrogen bonding groups that have been functionalized onto their surfaces. The result is that when two pieces of the composite are in close proximity, natural electrostatic forces bond them together. When the hydrogen bond is restored, the material has effectively healed itself.
The ratio of boron nitride nanosheets used in the composite determines the amount of heat or additional pressure that is needed to trigger the self-healing process. That said, with some percentages of boron nitride, it’s possible for the material to heal itself at room temperature simply by putting the broken pieces next to one another.
"We wanted to find an electronic material that would repair itself to restore all of its functionality, and do so after multiple breaks,” said Wang. “This is the first time that a self-healable material has been created that can restore multiple properties over multiple breaks, and we see this being useful across many applications,” said Wang.
You can see a video of the material performing its self-healing in real time below.
Wang told IEEE Spectrum that in continuing research, he and his team are working on integrating this material into working devices such as sensors and transistors to further demonstrate its utility.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.