Flexible electronics is the term coined for technologies that are assembled by layering electronic components onto flexible plastics such as Polyether ether ketone. Anyone who has bent around a wire has probably realized the same problem that all electronic components have, they break. The more you bend and flex the wire the more likely the wire will fail to function.
In recent years, there has been a growing interest in self-healing electrically conductive materials, specifically those that can repair themselves after experiencing modes of deformity and convolution. Until now, the major focus behind the advancement of flexible electronics has been aimed at self-healing electrical conductors as they tended to be the primary factor in enabling flexible circuits to function at all.
While this approach has been novel, a research team from Penn State has decided to shift the focus of advancing flexible technology to dielectrics. The terminology behind dielectrics typically denotes a material with high polarizability, but can be understood in some regard to be synonymous with an insulator as they can effectively function as one. The research team believes that the advancement of self-repairing electronics should involve conductors and dielectrics simultaneously.
“It is right that we require conductive elements in all types of circuits, but the fact cannot be ignored that we also require protection and insulation for microelectronics.” -Professor Qing Wang from Penn State.
Scientists and researchers have already created materials that could self-heal themselves naturally; restoring a few functions with little to no external force acting upon them. However, the problem has been the ability to restore all functions of the material, whether it is a dielectric, conductor, or some other flexible circuit component. These materials need to be able to restore all functions after experiencing break or deformation in order to function properly. Take for example the properties of a dielectric, surge protection, dynamism of thermal conductivity, voltage capacities, loss factors, resistance, and various others that typically define the parameters of capacitors. If one of these properties was not fully restored, such as thermal conductivity; the device would then be at risk of overheating, potentially destroying an essential component.
A flexible insulator. Courtesy of Penn State
The focus of the research team was based on the use of boron nitride (BN). The compound is heat- and chemically resistant, and exists in various stable forms that can be potentially used in nanotechnology. The research published in the Journal Advanced Functional Materials describes how the research team used a supramolecular approach in order to develop a vigorous polymer Nano-composite that has been strengthened with atomically thin sheets of boron nitride. The BN sheets are linked together by making use of hydrogen bonding groups that have been functionalized to the external layers.
What makes this material interesting is how it repairs itself when cut or deformed and when the pieces are placed in close proximity to each other, an electrostatic force is simultaneously generated on both ends. This will pull the pieces back together. The hydrogen bond is then restored, at this point, the material is considered to be “self-healed.” The amount of heat or pressure that is required to cause this process to occur is determined by the ratio of boron nitride sheets to the polymer, the fewer sheets, the easier it becomes for the material to repair itself. Certain BN structures are capable of completing the healing process at room temperature without the use of any other external force. The material has been able to restore itself with no significant changes in characteristics, providing great potential for the boron nitride compound. This also happens to be the first time that a self-healing material has been able to restore numerous properties after experiencing multiple breaks, according to lead researcher Qing Wang. You can watch a flexible insulator in action in the video below.