By Gary Thomas
Researchers at North Carolina State University, led by assistant professor, Dr. Yong Zhu, have employed silver nanowires to produce elastic conductors with high conductivity.
Conductor made of silver nanowires
The development has great impact on efforts being taken in the development of stretchable electronic circuits. Stretchable or elastic electronic devices offer capabilities beyond the realm of rigid electronic devices. A few possible applications include elastic antenna and displays for cell phones that enables them to stretch without affecting performance and electronic skin on robots to help them pick up fragile items without breaking them. The first challenge in developing elastic conductors is to ensure that the deformity does not hinder conductivity.
The method adopted by Zhu’s team involves the use of highly conductive silver nanowires that are embedded in a polymer capable of withstanding stretching without affecting silver’s conductivity. To fabricate this unique material, silver nanowires are first placed on silicon substrate. A liquid polymer is poured over the substrate which then traps the silver nanowires as it flows around them. On exposure to high heat, the polymer turns into elastic with the silver nanowire embedded within. The polymer can be peeled off the substrate. The polymer surface that has the nanowire embedded, buckles on stretching and relaxing the polymer. This buckled or wave-like shape on one side of the polymer helps the nanowires stay intact relative to one another and allows the material to be stretched to 50%of its length. The new stretchable conductors can be fabricated to patterned conductors by printing. The conductors were found to exhibit high robustness under constant mechanical loading.