PT  - JOURNAL ARTICLE
AU  - Fan, Wenxin
AU  - Shan, Caiyun
AU  - Guo, Hongyu
AU  - Sang, Jianwei
AU  - Wang, Rui
AU  - Zheng, Ranran
AU  - Sui, Kunyan
AU  - Nie, Zhihong
TI  - Dual-gradient enabled ultrafast biomimetic snapping of hydrogel materials
AID  - 10.1126/sciadv.aav7174
DP  - 2019 Apr 01
TA  - Science Advances
PG  - eaav7174
VI  - 5
IP  - 4
4099  - http://advances.sciencemag.org/content/5/4/eaav7174.short
4100  - http://advances.sciencemag.org/content/5/4/eaav7174.full
SO  - Sci Adv2019 Apr 01; 5
AB  - The design of materials that can mimic the complex yet fast actuation phenomena in nature is important but challenging. Herein, we present a new paradigm for designing responsive hydrogel sheets that can exhibit ultrafast inverse snapping deformation. Dual-gradient structures of hydrogel sheets enable the accumulation of elastic energy in hydrogels by converting prestored energy and rapid reverse snapping (<1 s) to release the energy. By controlling the magnitude and location of energy prestored within the hydrogels, the snapping of hydrogel sheets can be programmed to achieve different structures and actuation behaviors. We have developed theoretical model to elucidate the crucial role of dual gradients and predict the snapping motion of various hydrogel materials. This new design principle provides guidance for fabricating actuation materials with applications in tissue engineering, soft robotics, and active medical implants.