We also studied analogous ensembles of hard spinners driven to rotate in opposite directions by an applied torque. The dynamics of the spinners are governed by the Langevin equation. Simulations were performed for 16,384 spinners. References 3. Coarsening dynamics of binary liquids with active rotation2 Bio-inspired colloidal machine: bringing colloids to life S. Sabrina1, A. Brooks1, M. Spellings2,3, S. C. Glotzer2,3,4 and K. J. M. Bishop1 1Department of Chemical Engineering, The Pennsylvania State University, University Park, PA – 16802. 2Department of Chemical Engineering, 3Biointerfaces Institute and 4Department of Material Science and Engineering, University of Michigan, Ann Arbor, MI – 48109. 1. Motivation This work was supported as part of the Center for Bio-Inspired Energy Science (CBES), an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences under Award # DE- SC0000989. 4. Comparison with microscopic model2 Funding and Affiliations Acknowledgements 5. Current work: shape-directed actuation of spinners The governing equations were solved numerically on a square domain (𝐿× 𝐿) with periodic boundaries using semi-implicit (Adams-Bashforth) Fourier spectral method. The continuum model suggests that activity-induced flows influence the coarsening dynamics depending on the strength of rotation (𝛼) and strength of frictional damping (𝛽). Spinners – converting energy into rotational motion – phase separate via diffusion under strong frictional damping1. 1. Diffusion-controlled passive coarsening is observed for any strength of active rotation under conditions of strong frictional damping (𝛽≫1). 2. Accelerated active coarsening is observed under conditions of weak rotation (𝛼≪1) and weak frictional damping (𝛽≪1). 3. Multi-scale structures emerge under conditions of weak rotation(𝛼≪1) and zero frictional damping (𝛽= 0). 4. Vortex-doublets emerge under conditions of strong rotation (𝛼≫1) and zero frictional damping (𝛽= 0). Vortex-doublet stronger rotation less friction stronger rotation stronger rotation Compositional field Velocity field Domain size 2. Background and continuum model2 spinners 𝑅~ 𝑡1/3 phase separated fluid Assumptions 1. Incompressible, Newtonian fluid 2. Bulk properties (e.g., density ρ, viscosity 𝜂) same in both phases 3. Low Reynolds number 4. Neglect Capillary forces Strength of rotation, 𝛼= 𝜏Ф𝑇𝜂 Strength of friction, 𝛽= 𝑏𝐿2 𝜂 Here,𝜏is driving torque, Ф is equilibrium composition, 𝑇is time of diffusive unmixing over 𝐿, 𝐿is interfacial thickness, and 𝑏is friction coefficient. 1. Nguyen et. al., Physical Review Letter (2014) 2. Sabrina et. al., (submitted 2015) 3. Squires and Bazant, Journal of Fluid Mechanics (2006) 4. Gangwal et. al., Physical Review Letter (2008) 5. Yan et. al., Optical Materials Express (2011). Capture & Convert Move & Transport Sense & Respond Reconfigure & Adapt Heal & Repair Grow & Replicate ‘Life-like’ synthetic materials from colloids Distributed Centralized Vs. Energy conversion into motion Features of distributed actuation • Robust to failure(e.g., muscles) • Intelligent and adaptive behavior(e.g., bacterial swarms) 𝛽= 102 𝛼= 10−2 𝛽= 0 𝛽=0 𝑡= 105 𝑡= 105 𝑡= 105 𝑡= 104 𝑡= 104 𝛼′ = 0.25 𝑡= 105 𝛽′ = 10−2 𝛽′ = 1 𝛼′ = 0.25 Passive Active R i i i i d m dt     v F v F (a) Synthesis of different shapes of spinners by photolithography. (b) Selective electroless Ag plating of spinners5 (c) Experimental setup of ICEP-driven spinners. Continuity Convective Cahn-Hilliard Navier-Stokes active driving force frictional damping Induced-charged electro-osmotic flow (ICEO) in ac electric field can actuate particles using their shape asymmetry and surface heterogeneity3. We are synthesizing spinners of complex shape actuated by external fields such as electric and acoustic fields. The design of ICEP-driven spinners of complex shapes is guided by COMSOL simulations. Induced- charge electrophoresis (ICEP)4 Angular velocity of di