Tasoglu, S.Diller, E.Guven, S.Sitti, M.Demirci, U.2014-08-132014Tasoglu, S., E. Diller, S. Guven, M. Sitti, and U. Demirci. 2014. “Untethered micro-robotic coding of three-dimensional material composition.” Nature communications 5 (1): 3124. doi:10.1038/ncomms4124. http://dx.doi.org/10.1038/ncomms4124.2041-1723http://nrs.harvard.edu/urn-3:HUL.InstRepos:12717525Complex functional materials with three-dimensional micro- or nano-scale dynamic compositional features are prevalent in nature. However, the generation of three-dimensional functional materials composed of both soft and rigid microstructures, each programmed by shape and composition, is still an unsolved challenge. Herein, we describe a method to code complex materials in three-dimensions with tunable structural, morphological, and chemical features using an untethered magnetic micro-robot remotely controlled by magnetic fields. This strategy allows the micro-robot to be introduced to arbitrary microfluidic environments for remote two- and three-dimensional manipulation. We demonstrate the coding of soft hydrogels, rigid copper bars, polystyrene beads, and silicon chiplets into three-dimensional heterogeneous structures. We also use coded microstructures for bottom-up tissue engineering by generating cell-encapsulating constructs.en-UScoded materialsmicro-roboticsmagnetic actuationmicrogelsdirected assemblytissue engineeringJournal Article2014-08-1310.1038/ncomms4124