Fully Deformable Dual-Stopband Photonic Microcapsules via Microfluidic Core–Shell Emulsion Templates: Tunable Optical Properties and Mechanical Responsiveness

Photonic microcapsules with dual stopbands hold great potential in sensing and wearable electronics. However, existing systems face limited deformability and responsiveness to physical stimuli. In this study, we fabricated fully deformable dual-stopband photonic microcapsules using microfluidics-enabled core–shell double-emulsion templates. The core and shell parts of the microcapsules were an aqueous suspension of PNIPAM-co-AAC hydrogel particles and a poly(ethylene glycol) phenyl ether acrylate (PEGPEA) resin suspension of silica particles, respectively. Given that the core and shell parts were both deformable components, the resultant photonic microcapsules featured full deformability. Their structural colors can be regulated by tuning the particles’ diameters and volume fractions. The resultant microcapsules exhibited isotropic reflection spectra, overcoming angle dependence, and showed reversible color changes under mechanical compression. This work offers a scalable approach for multifunctional photonic microcapsules, paving the way for applications in microsensors, stress visualization, and adaptive wearable devices.