title: Writing in the granular gel medium.
abstract: Gels made from soft microscale particles smoothly transition between the fluid and solid states, making them an ideal medium in which to create macroscopic structures with microscopic precision. While tracing out spatial paths with an injection tip, the granular gel fluidizes at the point of injection and then rapidly solidifies, trapping injected material in place. This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written. With this method, we used silicones, hydrogels, colloids, and living cells to create complex large aspect ratio 3D objects, thin closed shells, and hierarchically branched tubular networks. We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times. This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies.
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Tapomoy
authors.initials: T
authors.lastname: Bhattacharjee
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Zehnder
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Kyle G
authors.initials: KG
authors.lastname: Rowe
authors.affiliation: Stanton College Preparatory, Jacksonville, FL 32209, USA.
authors.forename: Suhani
authors.initials: S
authors.lastname: Jain
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Nixon
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA. ; Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611, USA.
authors.forename: W Gregory
authors.initials: WG
authors.lastname: Sawyer
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA. ; J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA. ; Institute for Cell and Regenerative Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Angelini
keywords: 3D printin; carbopol; cell printing; granular gel; manufacturing; microgel; rapid prototyping; soft matter physics; yield stress