Fig. 3

Inverse design of a 4D printed bilayer actuator. (a) The ICN gel solution is composed of KarenzMOI-EG, DMAAm, and HPC. Upon 405nm light irradiation, the gel solution undergoes polymerization and transforms into a cured hydrogel. (b) TPU layer is printed by FDM technology. (c) The hydrogel layer is printed onto the TPU layer using SLA technology. (d) Design parameter is the length of the bilayer structure and desired shape is defined as the chord length \(l_c\). (e)-(k) Comparison between simulation and experimental results. Desired chord length 10 mm: (e) hydrogel thickness 1 mm; (f) hydrogel thickness 2 mm; (g) hydrogel thickness 3 mm. Desired chord length 20 mm: (h) hydrogel thickness 1 mm; (i) hydrogel thickness 2 mm; (j) hydrogel thickness 3 mm. (k) Quantitative comparison of the resulting chord lengths between simulations and experiments.