This new production method allows one colour after another to be placed in the appropriate indentations. | Graphic: M. Hu et al. (2024)

These microcapsules are filled with fluorescent dye that enable them to indicate stress-induced material damage in the micrometre range. As pressure increases, first the green capsules burst and release their dye, then the yellow and the blue. A research team led by Minghan Hu at ETH Zurich has now developed a process for capturing one capsule of each colour in microtraps on a silicone plate that can be integrated into materials that need to be monitored for damage, e.g., in aeroplanes.

M. Hu et al.: Self-Reporting Multiple Microscopic Stresses Through Tunable Microcapsule Arrays. Advanced Materials (2024)

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