While graphene aerogels have advantageous properties like extremely low weight, high porosity and good electrical conductivity, engineers who tried to use them to develop pressure sensors have encountered some difficulties.
Image credit: Nano Letters 2024
Specifically, many of these materials have an intrinsically stiff microstructure, which poses limits on their strain sensing capabilities. Researchers from Xi'an Jiaotong University, Northumbria University, UCLA, University of Alberta and other institutes recently introduced a new fabrication strategy for synthesizing aerogel metamaterials to overcome this limitation. This strategy fabricates a durable graphene oxide-based aerogel metamaterial that exhibits a remarkable sensitivity to human touch and motion.
The team's strategy for fabricating graphene oxide-based metamaterials is based on two key steps: the use of a dehydration technique known as freeze drying and a heat treatment process known as annealing.
The scientists explained that the pre-solution also contains a specific chemical that acts as graphene 'glue' to construct the honeycomb type cross section and that the structure configuration of the cross section on the dedicated plane was realized by thermal annealing, which can be tuned by micro-/nano-mechanics. Using this simple strategy, the buckled cross section was reportedly achieved on the first trial.
Using their proposed fabrication strategy, the team synthesized an anisotropic cross-linked chitosan and reduced graphene oxide (CCS-rGO) aerogel metamaterial. This material was found to exhibit a remarkable directional hyper elasticity, extraordinary durability, great mechanical and electrical performance, a long sensing range, and a very high sensitivity to stimuli of 121.45 kPa-1.
The research team is now conducting further studies aimed at developing promising metamaterials for various technological applications. In the future, their proposed fabrication strategy could contribute to the synthesis of additional graphene oxide-based aerogel metamaterials, which could advance human-machine interfaces for advanced health care and prosthetic devices.
Another development track for such sensors is in wind energy. The team is examining the potential of applying its materials/sensor research in the newly awarded EU COST Action CA23155, to advance the novel ocean tribology. This project focuses on offshore wind energy, which contributes to the global target of net zero and sustainability.