Browsing by Author "Kim, Min Jun"
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Item Imparting magnetic dipole heterogeneity to internalized iron oxide nanoparticles for microorganism swarm control(Journal of Nanoparticle Research, 3/17/2015) Kim, Paul Seung Soo; Becker, Aaron T.; Ou, Yan; Julius, Anak Agung; Kim, Min JunTetrahymena 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.Item Parallel Self-Assembly of Polyominoes Under Uniform Control Inputs(IEEE Robotics and Automation Letters, 6/15/2017) Manzoor, Sheryl; Sheckman, Samuel; Lonsford, Jarrett; Kim, Hoyeon; Kim, Min Jun; Becker, Aaron T.We present fundamental progress on parallel self-assembly using large swarms of microscale particles in complex environments, controlled not by individual navigation, but by a uniform, global, external force with the same effect on each particle. Consider a 2-D grid world, in which all obstacles and particles are unit squares, and for each actuation, particles move maximally until they collide with an obstacle or another particle. We present algorithms that, given an arbitrary 2-D structure, design an obstacle layout. When actuated, this layout generates copies of the input 2-D structure. We analyze the movement and spatial complexity of the factory layouts. We present hardware results on both a macroscale, gravity-based system, and a microscale, magnetically actuated system.