Kim, Paul Seung SooBecker, Aaron T.Ou, YanJulius, Anak AgungKim, Min Jun2019-10-012019-10-013/17/2015Copyright 2015 Journal of Nanoparticle Research. Recommended citation: Kim, Paul Seung Soo, Aaron Becker, Yan Ou, Anak Agung Julius, and Min Jun Kim. "Imparting magnetic dipole heterogeneity to internalized iron oxide nanoparticles for microorganism swarm control." Journal of Nanoparticle Research 17, no. 3 (2015): 144. DOI: 10.1007/s11051-014-2746-y URL: https://link.springer.com/article/10.1007/s11051-014-2746-y Reproduced in accordance with the original publisher’s licensing terms and with permission from the author(s).https://hdl.handle.net/10657/4900Tetrahymena pyriformis is a single cell eukaryote that can be modified to respond to magnetic fields, a response called magnetotaxis. Naturally, this microorganism cannot respond to magnetic fields, but after modification using iron oxide nanoparticles, cells are magnetized and exhibit a constant magnetic dipole strength. In experiments, a rotating field is applied to cells using a two-dimensional approximate Helmholtz coil system. Using rotating magnetic fields, we characterize discrete cells’ swarm swimming which is affected by several factors. The behavior of the cells under these fields is explained in detail. After the field is removed, relatively straight swimming is observed. We also generate increased heterogeneity within a population of cells to improve controllability of a swarm, which is explored in a cell model. By exploiting this straight swimming behavior, we propose a method to control discrete cells utilizing a single global magnetic input. Successful implementation of this swarm control method would enable teams of microrobots to perform a variety of in vitro microscale tasks impossible for single microrobots, such as pushing objects or simultaneous micromanipulation of discrete entities.en-USTetrahymena pyriformisIron oxide nanoparticlesMagnetotaxisSwarm controlMicrobotsArticle