It can be time-consuming to check components for wear and tear, whether it's on an aeroplane or in a nuclear power plant. Now a team of researchers has created dye-spilling capsules that can reveal faults quickly and clearly. A team from the University of Illinois has created a new polymer which can be applied to all kinds of materials in order to reveal potential damage more quickly than in the past. It consists of tiny microcapsules which contain pH-sensitive dyes, held in an epoxy resin. If the polymer is cracked, some of the microcapsules collapse, and their dye reacts with the epoxy to create a vivid red colour. The research is published in Advanced Materials.
Cracks of just 10 microns are enough to cause colour changes, and it can be applied to materials such as metals, polymers and glasses. The bigger the fault, the more intense the colour. You can see it in action in the image below, where the polymer has been applied to a steel plate which was subsequently scratched.
The team has also found the microcapusles to be stable -- so they don't leak their dye simply through ageing. Now, the team plans to try and combine the microcapsules with self-healing systems, so the reaction could also help solve the problem as well as alerting inspectors to the damage.