Fig. 5: Colloidal crystal materials with various compositions generated with the sacrificial scaffold.

a colloidal crystal hydrogel films fabricated with different precursors. The upper is the structure of the monomers, and the bottom is the fabricated hydrogel film (left: without sacrificial scaffold; right: with sacrificial scaffold). With the sacrificial scaffold, hydrogel films with bright structure color were obtained in spite of the compatibility of the monomers with nanoparticles. Scale bar: 3 mm. b Solid-state colloidal crystal microcube fabricated using pure PTTA as the precursor. (i) Model of the microcube (L = W = 50 μm, H = 25 μm). (ii) SEM image of the freeze-dried hydrogel microcube. (iii) Photo of the cube in DMF and (iv) in water. Scale bars: 25 μm. c Soild-state colloidal crystal 3D microstructure fabricated with pure PTTA as precursor. (i) Model of the gyroid microstructure. (ii) SEM image of the obtained gyroid microstructure. (iii) Top view of the gyroid microstructure. (iv) 3D view of the object. Scale bar: 20 μm. d Processing parameter of the temperature sensor based on polyNIPAAm microhydrogel array. e the optical picture of temperature sensors in the microfluidic chip. Scale bar: 1 cm, 0.5 cm and 50 μm. f Photo of the hydrogel array under different temperature. Scale bar: 50 μm. g Reflective spectra of the hydrogel cube 1 under different temperatures. h The maximum range of the reflection peak change of the hydrogel cubes under different temperatures. i Change the reflection peak of hydrogel cube 1 and cube 9 when the temperature switches between 20 °C and 40 °C for 10 cycles.