Fabrication and testing of surface ratchets primed with hydrophobic parylene and hexamethyldisilazane for transporting droplets

We demonstrate a way to transport droplets by an arrowed micropillar array surface with hydrophobic parylene. The lightly hydrophilic parylene surface could be changed to hydrophobic one by treating with fluorine-based plasma (CF4 or SF6). The droplet on this hydrophobic parylene surface with arrowed ratchets could be transported by a speaker, and the average measured velocity was 29 mm/s. Moreover, the authors compared driving performance of the parylene surface ratchets with the ones modified by the hexamethyldisilazane (HMDS) vapor. Both the results of using hydrophobic parylene and HMDS were better than the previous work.

[1]  Lung-Jieh Yang,et al.  Flapping wings with PVDF sensors to modify the aerodynamic forces of a micro aerial vehicle , 2007 .

[2]  Lei Jiang,et al.  Self-assembly of amino-functionalized monolayers on silicon surfaces and preparation of superhydrophobic surfaces based on alkanoic acid dual layers and surface roughening. , 2006, Journal of colloid and interface science.

[3]  Yu-Chong Tai,et al.  The marching velocity of the capillary meniscus in a microchannel , 2004 .

[4]  Gwo-Ching Wang,et al.  Effect of hydrophilic group on water droplet contact angles on surfaces of acid modified SiLK and Parylene polymers , 2006 .

[5]  J. Noordegraaf,et al.  C-shield parylene allows major weight saving for EM shielding of microelectronics , 1997, Proceedings. The First IEEE International Symposium on Polymeric Electronics Packaging, PEP '97 (Cat. No.97TH8268).

[6]  Stephen Y. Chou,et al.  Lithographically induced self-assembly of periodic polymer micropillar arrays , 1999 .

[7]  K. Najafi,et al.  Characterization of low-temperature wafer bonding using thin-film parylene , 2005, Journal of Microelectromechanical Systems.

[8]  Gareth H. McKinley,et al.  Superhydrophobic Carbon Nanotube Forests , 2003 .

[9]  H. Tsuji,et al.  Contact angle lowering of polystyrene surface by silver-negative-ion implantation for improving biocompatibility and introduced atomic bond evaluation by XPS , 1998 .

[10]  R. Blossey.  Self-cleaning surfaces — virtual realities , 2003, Nature materials.

[11]  Hans Christian von Baeyer.  The Lotus Effect , 2000 .

[12]  P. Audebert,et al.  Vapor deposition polymerization and reactive ion beam etching of poly(p-xylylene) films for waveguide applications , 1999 .

[13]  Self-cleaning Effects of Biomimetic Dry Adhesives , 2006, 2006 1st IEEE International Conference on Nano/Micro Engineered and Molecular Systems.

[14]  D. Beebe,et al.  Three-dimensional micro-channel fabrication in polydimethylsiloxane (PDMS) elastomer , 2000, Journal of Microelectromechanical Systems.

[15]  Hsieh-Cheng Han,et al.  Application of parylene-coated quartz crystal microbalance for on-line real-time detection of microbial populations. , 2009, Biosensors & bioelectronics.

[16]  Y. Tai,et al.  Photo-patternable gelatin as protection layers in low-temperature surface micromachinings , 2003 .

[17]  S. Cho,et al.  Creating, transporting, cutting, and merging liquid droplets by electrowetting-based actuation for digital microfluidic circuits , 2003 .

[18]  G. Poletti,et al.  Cold Plasma Treatment of PET Fabrics: AFM Surface Morphology Characterisation , 2003 .

[19]  Droplet Manipulation by Electrowetting on Polymer Dispersed Liquid Crystal , 2007, TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference.

[20]  K.F. Bohringer,et al.  Micro-Structured Surface Ratchets for Droplet Transport , 2007, TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference.

[21]  David J. Beebe,et al.  Fabrication of three-dimensional microfluidic systems by stacking molded polydimethylsiloxane (PDMS) layers , 1999, MOEMS-MEMS.

[22]  Shen Li,et al.  Improvement of hydrophobic properties of silk and cotton by hexafluoropropene plasma treatment , 2007 .

[23]  D. Ohlberg,et al.  Surface properties of platinum thin films as a function of plasma treatment conditions , 2003 .

[24]  Xun Zhu,et al.  Experiments and analysis on self-motion behaviors of liquid droplets on gradient surfaces , 2009 .

[25]  C. M. Ryu,et al.  Investigation of crystallinity effects on the surface of oxygen plasma treated low density polyethylene using X-ray photoelectron spectroscopy , 2003 .

[26]  Parallel Transportation of Droplets in a Multilayer Device by MEWOD , 2007, TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference.

[27]  J. Mueller,et al.  Hydrophobic coatings for MEMS applications , 2008 .

[28]  Y. Tai,et al.  Photo-patternable gelatin as protection layers in surface micromachinings , 2002, Technical Digest. MEMS 2002 IEEE International Conference. Fifteenth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.02CH37266).

[29]  C. Wong,et al.  Optimizing geometrical design of superhydrophobic surfaces for prevention of microelectromechanical system (MEMS) stiction , 2006, 56th Electronic Components and Technology Conference 2006.

[30]  Lung-Jieh Yang,et al.  Electro-Hydro-Dynamic (EHD) Micropumps with Electrode Protection by Parylene and Gelatin , 2005 .

[31]  W. Shih,et al.  Buckled-type valves integrated by parylene micro-tubes , 2005, The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05..

[32]  D. Yao,et al.  Rapid pattern transfer of biomimetic surface structures onto thermoplastic polymers , 2007 .

[33]  E. Selli,et al.  Characterisation of poly(ethylene terephthalate) and cotton fibres after cold SF6 plasma treatment , 2001 .

[34]  Akira Fujishima,et al.  Structural color and the lotus effect. , 2003, Angewandte Chemie.

[35]  Tae Song Kim,et al.  Effect of oxygen plasma treatment on adhesion improvement of au deposited on Pa-c substrates , 2004 .

[36]  V. Pavarajarn,et al.  Enhancement of the hydrophobicity of silk fabrics by SF6 plasma , 2008 .

[37]  Kerstin Länge,et al.  Chemical modification of parylene C coatings for SAW biosensors , 2007 .

[38]  U. Steiner,et al.  Super-hydrophobic surfaces made from Teflon. , 2007, Soft matter.