Metamaterials are artificial substances that are structurally engineered to have properties not typically found in nature. To date, almost all metamaterials have been made from inorganic materials such as silicon and copper1,2, which have unusual electromagnetic or acoustic properties1,5 that allow them to be used, for example, as invisible cloaks6,9, superlenses10-12 or super absorbers for sound13. Here, we show that metamaterials with unusual mechanical properties can be prepared using DNA as a building block. We used a polymerase enzyme to elongate DNA chains and weave them non-covalently into a hydrogel. The resulting material, which we term a meta-hydrogel, has liquid-like properties when taken out of water and solid-like properties when in water. Moreover, upon the addition of water, and after complete deformation, the hydrogel can be made to return to its original shape. The meta-hydrogel has a hierarchical internal structure and, as an example of its potential applications, we use it to create an electric circuit that uses water as a switch.
Bibliographical noteFunding Information:
The authors thank L. Archer and R. Mallavajula for helping with the mechanical test and C. Hui for insightful discussions. The authors also thank J. March, J. Hunter and T. Walter for proofreading this manuscript and Z. Li for discussions and suggestions. L.C. acknowledges support from the CAS/SAFEA International Partnership Program for Creative Research Teams. The present work was partially supported by grants from the United States Department of Agriculture (USDA) and the Department of Defense (DOD).
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Biomedical Engineering
- Materials Science(all)
- Condensed Matter Physics
- Electrical and Electronic Engineering