Evaporative micro-particle self assembly influenced by capillary evacuation

Shao, Fen Fen; Ng, Tuck Wah; Efthimiadis, Jim; Somers, Anthony; Schwalb, Willem Heinrich

doi:10.1016/j.jcis.2012.02.071

Cited by 12 publications

(7 citation statements)

References 33 publications

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“…Some factors influencing aggregation are size and concentration, surface charge level, and the nature and concentration of ions in the suspending medium. While there may also be a possibility of surface sticking at play, the contribution of this is not likely to be significant as found in recent studies 22 . A different scenario is played out with the bacteria sample.…”

Section: Trapping Experimentationmentioning

confidence: 68%

Modeling and fabrication of scale-like cantilever for cell capturing

Liu

Muradoglu

2013

SPIE Proceedings

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The micro-domain provides excellent conditions for performing biological experiments on small populations of cells and has given rise to the proliferation of so-called lab-on-a-chip devices. In order to fully utilize the benefits of cell assays, means of retaining cells at defined locations over time are required. Here, the creation of scale-like cantilevers, inspired by biomimetics, on planar silicon nitride (Si 3 N 4 ) film using focused ion beam machining is described. Using SEM imaging, regular tilting of the cantilever with almost no warping of the cantilever was uncovered. Finite element analysis showed that the scale-like cantilever was best at limiting stress concentration without difficulty in manufacture and having stresses more evenly distributed along the edge. It also had a major advantage in that the degree of deflection could be simply altered by changing the central angle. From a piling simulation conducted, it was found that a random delivery of simulated particles on to the scale-like obstacle should create a triangular collection. In the experimental trapping of polystyrene beads in suspension, the basic triangular piling structure was observed, but with extended tails and a fanning out around the obstacle. This was attributed to the aggregation tendency of polystyrene beads that acted on top of the piling behavior. In the experiment with bacterial cells, triangular pile up behind the cantilever was absent and the bacteria cells were able to slip inside the cantilever's opening despite the size of the bacteria being larger than the gap. Overall, the fabricated scale-like cantilever architectures offer a viable way to trap small populations of material in suspension.

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Section: Trapping Experimentationmentioning

confidence: 68%

Modeling and fabrication of scale-like cantilever for cell capturing

Liu

Muradoglu

2013

SPIE Proceedings

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“…Most of them are of orders of several or hundred piconewton, which are 8-12 orders higher than that of the inertial force F , indicating that microparticles at the contact line are nearly in force equilibrium. To ensure such a quasi-static process, we suppose that microparticles near the liquid-vapor interface experience a capillary force, FS, given by [3,23,24] …”

Section: Resultsmentioning

confidence: 99%

“…Using molecular dynamic simulation, Li et al [22] predicted three styles of contact line motion including complete slipping, alternate pinning-depinning, and complete pinning. Different from Jung et al [15], Wong et al [16], Weon et al [18] and Chhasatia and Sun [17], the capillary force is supposed to act on the particle along a declined redirection rather than parallel to the solid-liquid interface [23,24]. Combining all the above studies, we aim at setting up a novel self-pinning mechanism.…”

Section: Introductionmentioning

confidence: 98%

Quasi-static motion of microparticles at the depinning contact line of an evaporating droplet on PDMS surface

Xia

Zheng

et al. 2017

Sci. China Phys. Mech. Astron.

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In this paper, evaporation of sessile water droplets containing fluorescent polystyrene (PS) microparticles on polydimethylsiloxane (PDMS) surfaces with different curing ratios was studied experimentally using laser confocal microscopy. At the beginning, there were some microparticles located at the contact line and some microparticles moved towards the line. Due to contact angle hysteresis, at first both the contact line and the microparticles were pinned. With the depinning contact line, the microparticles moved together spontaneously. Using the software ImageJ, the location of contact lines at different time were acquired and the circle centers and radii of the contact lines were obtained via the least square method. Then the average distance of two neighbor contact lines at a certain time interval was obtained to characterize the motion of the contact line. Fitting the distance-time curve at the depinning contact line stage with polynomials and differentiating the polynomials with time, we obtained the velocity and acceleration of both the contact line and the microparticles located at the line. The velocity and the maximum acceleration were, respectively, of the orders of 1 µm/s and 20-200 nm/s 2 , indicating that the motion of the microparticles located at the depinning contact line was quasi-static. Finally, we presented a theoretical model to describe the quasi-static process, which may help in understanding both self-pinning and depinning of microparticles.

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“…While there may also be a possibility of surface sticking at play, the contribution of this is not likely to be signicant as found in recent studies. 28 A different scenario is played out with the bacteria sample. Here, the triangular pile up before the cantilever is absent.…”

Section: Resultsmentioning

confidence: 99%