The KIST-Stanford research team has developed a new material that simultaneously possesses high stretchability, high electrical conductivity, and self-healability even after being subjected to severe mechanical strain. The team dispersed silver micro-/nanoparticles throughout the highly stretchable and self-healable polymer material to achieve a new design for a nanocomposite material.
The team includes researcher Hyunseon Seo and senior researcher Dr. Donghee Son of the Korea Institute of Science and Technology's Biomedical Research Institute and postdoctoral candidate Dr. Jiheong Kang and Professor Zhenan Bao of Stanford University (chemical engineering).
Enhancing Capability of Existing Wearables
This material can be utilized as an interconnect, because it has the same properties as existing wearable materials as with high electrical conductivity and stretchability. These properties allow the stable transmission of electricity and data from the human body to electronic devices.
During tests, the material developed by the KIST team was utilized as an interconnect and attached to the human body to allow for the measurement of biometric signals in real time. The signals were then transmitted to a robotic arm, which successfully and accurately imitated (in real time) the movements of a human arm.
Increased Conductivity under High Strain
In the typical materials, the electrical conductivity (and thus performance) decreases when the shape of the materials is changed by an applied tensile strain. However, the new material shows a dramatic increase in conductivity under a tensile strain of 3,500%. In fact, electrical conductivity rose over 60-fold, achieving the highest conductivity level reported worldwide so far. Even if the material is damaged or completely cut through, it is able to self-heal, a property that is already gaining attention from academia.
Self-Improvement of Electrical Conductivity
The KIST team investigated phenomena that have not yet been studied in existing conductive materials. The phenomenon exhibited in the new material developed by the team is electrical "self-boosting". This phenomenon refers to the self-improvement of electrical conductivity through the rearrangement and self-alignment of a material's micro-/nanoparticles when the material is stretched. The team also discovered the mechanism of such dynamic behavior of micro-/nanoparticles by using SEM and microcomputed tomography (μ-CT) analyses.
Seo said, "Our material is able to function normally even after being subjected to extreme external forces that cause physical damages, and we believe that it will be actively utilized in the development and commercialization of next-generation wearable electronic devices,".
"Because the outcome of this study is essentially the foundational technology necessary for the development of materials that can be used in major areas of the Fourth Industrial Revolution, such as medical engineering, electrical engineering, and robotics, we expect that it will be applicable to diverse fields." added Dr. Donghee Son.