The Movement of a Water Droplet on a Gradient Surface Prepared by Photodegradation

Ito, Yoshihiro; Heydari, Mojgan; Hashimoto, Ayako; Konno, Tomohiro; Hirasawa, Ayaka; Hori, Satomi; Kurita, Kimio; Nakajima, Akira

doi:10.1021/la0624992

Cited by 158 publications

(110 citation statements)

References 50 publications

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“…34,35,37 This abrupt increase in wettability, and thus decrease of hydrophobic surface energy, is the result of SAM degradation, under UV-light exposure. 34,35 This shift in water CA measurements between exposed and not exposed SAM can qualitatively explain the transition of LC anchoring from homeotropic to approximately planar.…”

Section: Resultsmentioning

confidence: 99%

Sub-millisecond nematic liquid crystal switches using patterned command layer

Cattaneo

Kouwer

Rowan

et al. 2013

Journal of Applied Physics

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Section: Resultsmentioning

confidence: 99%

Sub-millisecond nematic liquid crystal switches using patterned command layer

Cattaneo

Kouwer

Rowan

et al. 2013

Journal of Applied Physics

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“…Our motivation is to realize a sperm testing device based on the droplet manipulation on a switchable surface. Conventionally, switchable surfaces utilize changes in molecular conformation of a selfassembled monolayer (SAM) under external stimuli [1][2][3][4][5][6][7][8][9][10][11]. However, a fluidic drop usually refuses to move toward more hydrophilic regions on the SAM-based switchable surfaces because the weak chemical gradient cannot overcome the hysteresis of the surface.…”

Section: Introductionmentioning

confidence: 99%

A Sperm Testing Device on a Liquid Crystal and Polymer Composite Film

Lin¹,

Chu²,

Chu³

et al. 2013

J Nanomed Nanotechol

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Developing a handy sperm testing device is important since sperm quality is a significant factor for fertility potential. In this paper, we demonstrate a sperm testing device based on a switchable surface, a liquid crystal and polymer composite film (LCPCF). The wettability of LCPCF is electrically switchable due to the electrically tunable orientations of liquid crystal molecules. In experiments, two motions of a semen drop on switchable surface of LCPCF are observed: back-and-forth stretches and collapses of semen drops. The better quality spermatozoa results in back-and-forth stretches of a semen drop on LCPCF; otherwise, the semen drop collapses. The motility and concentration of semen can also be sensed by the stretch distance and collapse distance of semen drops, respectively. The mechanism of back-and-forth stretches of semen drops results from fertile sperms swimming against the flow with the periodic changes of the orientation of LC molecules with pulsed voltages. The mechanism of collapses of semen drops results from the washed-away infertile sperms which are deposited on LCPCF and then re-modify surface of LCPCF. Potential applications for this device include sperm testers and microfluidic devices for Assisted Reproductive Technology.

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“…In the first case, droplets are formed and manipulated on a surface or interface through the modulation of surface stresses by thermal [26], electrical [27], optical [12], photoresponsive [28] or chemical means [29]. Heat carried by a focused laser beam was also used to move droplets [30] or continuous fluid interfaces [31] on liquid or solid substrates, thus simplifying microfabrication since actuators are not embedded in the substrate anymore.…”

Section: Introductionmentioning

confidence: 99%

Laser microfluidics: fluid actuation by light

Delville¹,

Vincent²,

Schroll³

et al. 2009

J. Opt. A: Pure Appl. Opt.

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The development of microfluidic devices is still hindered by the lack of robust fundamental building blocks that constitute any fluidic system. An attractive approach is optical actuation because light field interaction is contactless and dynamically reconfigurable, and solutions have been anticipated through the use of optical forces to manipulate microparticles in flows. Following the concept of "optical chip" advanced from the optical actuation of suspensions, we propose in this survey new routes to extend this concept to microfluidic two-phase flows. First, we investigate the destabilization of fluid interfaces by the optical radiation pressure and the formation of liquid jets. We analyze the droplet shedding from the jet tip and the continuous transport in laser-sustained liquid channels. In a second part, we investigate a dissipative light-flow interaction mechanism consisting in heating locally two immiscible fluids to produce thermocapillary stresses along their interface. This opto-capillary coupling is implemented in adequate microchannel geometries to manipulate two-phase flows and propose a contactless optical toolbox including valves, droplet sorters and switches, droplet dividers or droplet mergers. Finally, we discuss radiation pressure and opto-capillary effects in the context of the "optical-chip" where flows, channels and operating functions would all be performed optically on the same device.

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The Movement of a Water Droplet on a Gradient Surface Prepared by Photodegradation

Cited by 158 publications

References 50 publications

Sub-millisecond nematic liquid crystal switches using patterned command layer

Sub-millisecond nematic liquid crystal switches using patterned command layer

A Sperm Testing Device on a Liquid Crystal and Polymer Composite Film

Laser microfluidics: fluid actuation by light

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