Colorimetric and self-sealing photonic crystal film for early detection of SF₆ leakage in gas-insulated equipment

Sulfur hexafluoride (SF6), widely used in gas-insulated switchgear (GIS), is a potent greenhouse gas with high global warming potential, making leakage reduction a critical challenge for the power industry. In practice, SF6 leaks often occur at structural interfaces and are difficult to detect early using conventional pressure-based or manual inspection methods, leading to delayed response and increased environmental impact. To address this issue, this paper proposes a flexible colorimetric photonic crystal film for early and location-specific SF6 leak detection. The film can be directly applied to leakage-prone areas and enables passive visualization of leaks. Escaping gas induces mechanical deformation of the film, causing a reversible structural color change due to the shift of the Bragg reflection peak, which can be observed by the naked eye. This allows rapid leak identification without external power or complex instruments. To enhance functionality, the film is infused with an ionic liquid, improving flexibility and providing preliminary self-sealing by partially filling micro-gaps.