title: Stretchable living materials and devices with hydrogel-elastomer hybrids hosting programmed cells.
abstract: Living systems, such as bacteria, yeasts, and mammalian cells, can be genetically programmed with synthetic circuits that execute sensing, computing, memory, and response functions. Integrating these functional living components into materials and devices will provide powerful tools for scientific research and enable new technological applications. However, it has been a grand challenge to maintain the viability, functionality, and safety of living components in freestanding materials and devices, which frequently undergo deformations during applications. Here, we report the design of a set of living materials and devices based on stretchable, robust, and biocompatible hydrogel-elastomer hybrids that host various types of genetically engineered bacterial cells. The hydrogel provides sustainable supplies of water and nutrients, and the elastomer is air-permeable, maintaining long-term viability and functionality of the encapsulated cells. Communication between different bacterial strains and with the environment is achieved via diffusion of molecules in the hydrogel. The high stretchability and robustness of the hydrogel-elastomer hybrids prevent leakage of cells from the living materials and devices, even under large deformations. We show functions and applications of stretchable living sensors that are responsive to multiple chemicals in a variety of form factors, including skin patches and gloves-based sensors. We further develop a quantitative model that couples transportation of signaling molecules and cellular response to aid the design of future living materials and devices.
authors.affiliation: Soft Active Materials Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Xinyue
authors.initials: X
authors.lastname: Liu
authors.affiliation: Synthetic Biology Group, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Tzu-Chieh
authors.initials: TC
authors.lastname: Tang
authors.affiliation: Synthetic Biology Group, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139.|Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Eléonore
authors.initials: E
authors.lastname: Tham
authors.affiliation: Soft Active Materials Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Hyunwoo
authors.initials: H
authors.lastname: Yuk
authors.affiliation: Soft Active Materials Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Shaoting
authors.initials: S
authors.lastname: Lin
authors.affiliation: Synthetic Biology Group, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139; timlu@mit.edu zhaox@mit.edu.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.|Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Lu
authors.affiliation: Soft Active Materials Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; timlu@mit.edu zhaox@mit.edu.|Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Xuanhe
authors.initials: X
authors.lastname: Zhao
mesh_terms: D054742:Acyl-Butyrolactones / Q000032:analysis / Q000494:pharmacology; D001672:Biocompatible Materials / Q000138:chemical synthesis*; D001692:Biological Transport; D015374:Biosensing Techniques; D018914:Cells, Immobilized / Q000378:metabolism; D002616:Chemical Engineering / Q000379:methods; D020724:Elastomers / Q000138:chemical synthesis*; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics* / Q000378:metabolism; D020100:Hydrogels / Q000138:chemical synthesis*; D007544:Isopropyl Thiogalactoside / Q000032:analysis / Q000494:pharmacology; D053038:Quorum Sensing
chemical_list: D054742:Acyl-Butyrolactones; D001672:Biocompatible Materials; D020724:Elastomers; D020100:Hydrogels; D049452:Green Fluorescent Proteins; D007544:Isopropyl Thiogalactoside
keywords: biochemical sensors; genetically engineered bacteria; hydrogels; synthetic biology; wearable devices