Programmable droplet manipulation by a magnetic-actuated robot

We demonstrate a magnetic-actuated robot with adjustable structure to operate fluids for transport, split, release, and rotation. Droplet manipulations are fundamental to numerous applications, such as water collection, medical diagnostics, and drug delivery. Structure-based liquid operations have been widely used both in nature and in artificial materials. However, current strategies depend mainly on fixed structures to realize unidirectional water movement, while multiple manipulation of droplets is still challenging. Here, we propose a magnetic-actuated robot with adjustable structures to achieve programmable multiple manipulations of droplets. The adjustable structure redistributes the resisting forces from the front and rear ends of the droplets, which determine the droplet behaviors. We can transport, split, release, and rotate the droplets using the robot. This robot is universally applicable for manipulation of various fluids in rough environments. These findings offer an efficient strategy for automated manipulation of droplets.

[1]  Noel S Ha,et al.  Ionic-surfactant-mediated electro-dewetting for digital microfluidics , 2019, Nature.

[2]  Xuanhe Zhao,et al.  Ferromagnetic soft continuum robots , 2019, Science Robotics.

[3]  Po-Hsun Huang,et al.  Digital acoustofluidics enables contactless and programmable liquid handling , 2018, Nature Communications.

[4]  Olli Ikkala,et al.  Switchable Static and Dynamic Self-Assembly of Magnetic Droplets on Superhydrophobic Surfaces , 2013, Science.

[5]  Christophe Clanet,et al.  Water ring-bouncing on repellent singularities. , 2018, Soft matter.

[6]  Yi Du,et al.  Fast Responsive and Controllable Liquid Transport on a Magnetic Fluid/Nanoarray Composite Interface. , 2016, ACS nano.

[7]  Tza‐Huei Wang,et al.  Full‐Range Magnetic Manipulation of Droplets via Surface Energy Traps Enables Complex Bioassays , 2013, Advanced materials.

[8]  Yuanjin Zhao,et al.  Emerging Droplet Microfluidics. , 2017, Chemical reviews.

[9]  James C. Weaver,et al.  Condensation on slippery asymmetric bumps , 2016, Nature.

[10]  Oswald Prucker,et al.  Artificial Cilia: Generation of Magnetic Actuators in Microfluidic Systems , 2011 .

[11]  J. C. Chen,et al.  Fast drop movements resulting from the phase change on a gradient surface. , 2001, Science.

[12]  Dongliang Tian,et al.  Multifunctional Magnetocontrollable Superwettable‐Microcilia Surface for Directional Droplet Manipulation , 2019, Advanced science.

[13]  N. Gershenfeld,et al.  Microfluidic Bubble Logic , 2006, Science.

[14]  Shawn A. Chester,et al.  Printing ferromagnetic domains for untethered fast-transforming soft materials , 2018, Nature.

[15]  M. Möller,et al.  Hybrid nanostructured particles via surfactant-free double miniemulsion polymerization , 2018, Nature Communications.

[16]  Jin Zhai,et al.  Directional water collection on wetted spider silk , 2010, Nature.

[17]  Lei Jiang,et al.  A multi-structural and multi-functional integrated fog collection system in cactus , 2012, Nature Communications.

[18]  Yanlei Yu,et al.  Photocontrol of fluid slugs in liquid crystal polymer microactuators , 2016, Nature.

[19]  George M. Whitesides,et al.  Coding/Decoding and Reversibility of Droplet Trains in Microfluidic Networks , 2007, Science.

[20]  P. Levkin,et al.  Droplet Microarrays: From Surface Patterning to High‐Throughput Applications , 2018, Advanced materials.

[21]  Metin Sitti,et al.  Small-scale soft-bodied robot with multimodal locomotion , 2018, Nature.

[22]  H. Anders,et al.  Crystal nephropathies: mechanisms of crystal-induced kidney injury , 2017, Nature Reviews Nephrology.

[23]  J. M. Bush,et al.  Surface Tension Transport of Prey by Feeding Shorebirds: The Capillary Ratchet , 2008, Science.

[24]  Lei Jiang,et al.  Applications of Bio‐Inspired Special Wettable Surfaces , 2011, Advanced materials.

[25]  Youmin Hou,et al.  Directional transport of high-temperature Janus droplets mediated by structural topography , 2016, Nature Physics.

[26]  W. Gregory Sawyer,et al.  Self-assembled micro-organogels for 3D printing silicone structures , 2017, Science Advances.

[27]  Doris Vollmer,et al.  How drops start sliding over solid surfaces , 2017, Nature Physics.

[28]  Kripa K. Varanasi,et al.  Electrostatically driven fog collection using space charge injection , 2018, Science Advances.

[29]  Bin Su,et al.  Utilizing superhydrophilic materials to manipulate oil droplets arbitrarily in water , 2011 .

[30]  Zhicheng Long,et al.  Fundamentals of magnet-actuated droplet manipulation on an open hydrophobic surface. , 2009, Lab on a chip.

[31]  Xuechang Zhou,et al.  Mechano-regulated surface for manipulating liquid droplets , 2017, Nature Communications.

[32]  F. Coe,et al.  Stopping the Stones , 2010, Science.

[33]  Mingjie Liu,et al.  High-speed transport of liquid droplets in magnetic tubular microactuators , 2018, Science Advances.

[34]  Xize Niu,et al.  Combinatorial microfluidic droplet engineering for biomimetic material synthesis , 2016, Science Advances.

[35]  Qiang Huang,et al.  A bioinspired multilegged soft millirobot that functions in both dry and wet conditions , 2018, Nature Communications.

[36]  Guobao Xu,et al.  Artemisinin-Luminol Chemiluminescence for Forensic Bloodstain Detection Using a Smart Phone as a Detector. , 2017, Analytical chemistry.