Remote Manipulation of Droplets on a Flexible Magnetically Responsive Film

The manipulation of droplets is used in a wide range of applications, from lab-on-a-chip devices to bioinspired functional surfaces. Although a variety of droplet manipulation techniques have been proposed, active, fast and reversible manipulation of pure discrete droplets remains elusive due to the technical limitations of previous techniques. Here, we describe a novel technique that enables active, fast, precise and reversible control over the position and motion of a pure discrete droplet with only a permanent magnet by utilizing a magnetically responsive flexible film possessing actuating hierarchical pillars on the surface. This magnetically responsive surface shows reliable actuating capabilities with immediate field responses and maximum tilting angles of ???90??. Furthermore, the magnetic responsive film exhibits superhydrophobicity regardless of tilting angles of the actuating pillars. Using this magnetically responsive film, we demonstrate active and reversible manipulation of droplets with a remote magnetic force.open0

Wetting theory for small droplets on textured solid surfaces

This work is supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2016M3D1A1900038). N.M.P. is supported by the European Research Council (ERC StG Ideas 2011 BIHSNAM n. 279985, ERC PoC 2015 SILKENE nr. 693670), by the European Commission under the Graphene Flagship (WP14 Polymer Composites, no. 696656). N.M.P. thanks Profs. Della Volpe and Siboni for useful comments on the paper

Small-Intestinal Manifestations of Dextran Sulfate Sodium Consumption in Rats and Assessment of the Effects of Lactobacillus fermentum BR11

© Springer Science+Business Media, 2008The dextran sulfate sodium (DSS) colitis model has been utilized to screen for novel therapeutics for ulcerative colitis. Evidence suggests the small intestine may also be affected by DSS. We characterized the effects of DSS on the small intestine and assessed the potential for Lactobacillus fermentum BR11 to modify or normalize DSS-induced changes. Rats were allocated to three groups, Water + Vehicle, DSS + Vehicle, and DSS + L. fermentum BR11. BR11 was administered twice daily for 14 days. DSS (2%) was provided from days 7 to 14. Small-intestinal tissue was analyzed for sucrase activity, histology, and crypt cell proliferation. Increased ileum crypt depth and cell proliferation was observed in DSS-treated rats compared to controls (P < 0.05). BR11 normalized these parameters. While DSS predominantly induces colonic damage, minor morphological alterations were also detected in the distal small intestine. L. fermentum BR11 normalized these features.Mark S. Geier, Cassie L. Smith, Ross N. Butler and Gordon S. Howart

A quantitative experimental study of wetting hysteresis on discrete and continuous chemical heterogeneities

Chemically heterogeneous surfaces are well known to induce contact angle hysteresis due to the local energy barriers that oppose contact line movement. In many cases, the surface heterogeneity is discontinuous, i.e. discrete regions of different wettability exist, which leads to pinning of the contact line at boundaries between regions. Pinning on individual rows of microscopic defects arranged in a square lattice can be sensed using a Wilhelmy balance to reveal discrete stick-slip motion. For defects more wettable than the matrix with a lattice spacing of 28 µm, the advancing contact line slips over ~10 rows in a single slip step, while the receding contact line stick-slips between individual rows of defects. Single, millimetre-scale defects were used to assess the energy involved when a contact line advances or recedes over a hydrophilic (more wettable) defect. Quantitative information about defect-induced hysteresis in relation to defect dimensions is obtained. The crucial importance of wetting boundaries is highlighted with an experimental example of a surface that is heterogeneous yet, due to the continuously changing pattern, does not exhibit contact angle hysteresis