Based around the full lifecycle of electronics and reducing the amount of e-waste we produce, the technique relies on polymers that can be broken down by solvents without damaging the integrated nanowires. Once a device has been used, the polymer matrix containing the silver nanowires is dissolved, leaving behind just the nanowire network. The nanowires are then placed in a separate solvent and ultrasound is used to disentangle them, separating them out of the network.
“There is a lot of interest in recycling electronic materials because we want to both reduce electronic waste and maximise the use we get out of rare or costly materials,” said Yuxuan Liu, a PhD student at North Carolina State University (NC State), and first author of the research paper, which features in Advanced Electronic Materials.
“We’ve demonstrated an approach that allows us to recycle nanowires, and that we think could be extended to other nanomaterials – including nanomaterials containing noble and rare-earth elements.”
For their demonstration, the NC State team first created a sensor, then applied their recycling process to separate the polymer and the nanowires, reusing the nanowires to create a brand-new wearable sensor. While there was minor degradation in the properties of the nanowire network after each life cycle, the researchers found that the nanowires could be recycled four times without harming the sensor’s performance. After four life cycles, it is possible to improve the performance of the nanowire network by introducing new silver nanowires into the mix.
“In our approach, a silver nanowire network is separated from the rest of the materials in a device,” said corresponding author Yong Zhu, a Mechanical and Aerospace Engineering at NC State. “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.”