Researchers have demonstrated how to recycle nanowires from the electronic circuits after their lifetime.
Recycling and reusing electronic materials is important as it reduces the waste in landfills and maximizes the use of some rare or costly materials. Researchers across the globe are trying to develop recyclable electronic circuits. Recently, researchers from the North Carolina University have suggested a low-cost technique  for retrieving nanowires from electronic devices that have reached the end of their utility. The retrieved nanowires can be used in new devices. According to the researchers, this is a big step towards sustainable electronics.
“Our recycling technique differs from conventional recycling,” says Yong Zhu, corresponding author of the paper and the Andrew A. Adams Distinguished Professor of Mechanical and Aerospace Engineering at NC State. “When you think about recycling a glass bottle, it is completely melted down before being used to create another glass object. In our approach, a silver nanowire network is separated from the rest of the materials in a device. That network is then disassembled into a collection of separate silver nanowires in solution. Those nanowires can then be used to create a new network and incorporated into a new sensor or other devices.”
The first step towards making recyclable nanowires is to design a device using polymers that are soluble in solvents that will not also dissolve the nanowires. After the device has completed its lifetime, the polymer consisting of the nanowire is dissolved, which leaves behind the nanowire network. The retrieved network is placed in another solvent and hit with an ultrasound to disperse them from the network.
For the proof of theory, they made a wearable patch that could be used to track a patient’s temperature and hydration. It consisted of silver nanowires onto a polymer material. After their usage, the researchers performed the recycling process, and made a new sensor out of it. They observed a minor degradation in the properties of the nanowire network after each life cycle. Moreover, they figured out that the nanowires can be recycled four times before significant degradation happens.
After four cycles, the performance of the nanowire network can be improved by introducing new silver nanowires into the mix.
“The approach we’ve demonstrated here could be used to recycle other nanomaterials—such as nanoparticles, carbon nanotubes, other types of nanowires, and two-dimensional materials—as long as they are used in the form of a network,” Zhu says.
The work is published in the journal Advanced Electronic Materials.
