A tunable biological tissue-inspired photonic fluid

We design an amorphous material with a full photonic band gap inspired by how cells pack in biological tissues. A physical parameter based by how cells adhere with one another and regulate their shapes can continuously tune the photonic band gap size as well as the bulk mechanical properties of the material. The photonic band gap persists well through a solid-fluid phase transition characterized by a vanishing shear modulus. This property gives rise to a photonic fluid which overcomes many of the limitations of previously proposed photonic materials due to its insensitivity to structural defects and robustness with respect to fluid flow, rearrangements and thermal fluctuations. Interestingly, we also find the patterns generated here to be hyperuniform, however hyperuniformity does not guarantee the presence of a photonic band gap. Rather we find the size of the photonic band gap is closely coupled to the amount of short range order. The design proposed here uses a physical interaction that can be realized in experiment via self-assembly engineering. In particularly, emulsion droplets or nanoparticles grafted with polymers should be ideal for constructing such structures.