Ultrafast mechano-responsive photonic hydrogel towards multicolor displays via the pressure sensation

In this work, the magnetic assembly combined with fast photopolymerization is applied for the preparation of mechano-responsive photonic hydrogel. The as-prepared hydrogel exhibits switchable color with ultrafast speed (Δλ/t=~1.2 nm/ms) across a broad wavelength range (Δλ=~250 nm), which is attributed to fast changing of the interparticle distance d of one dimensional (1 D) Fe₃O₄ nanoparticle chains fixed inside the hydrogel matrix in response to compressive force stimulus. The pressure chromatic sensitivity is high (Δλ/σ=20–40 nm kPa⁻¹) in touch region. With the aid of 3D printing technique, we innovatively demonstrate simultaneous multicolor displays on the hydrogel.