Beetle Inspired Electrospray Vapor Chamber

Zhao, Yuejun; Boreyko, Jonathan B.; Chiang, Meng-Han; Baker, Christopher H.; Chen, Chuan‐Hua

doi:10.1115/mnhmt2009-18498

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…Applications such as condenser surfaces for vapor chambers, cell cultivation, and offset printing plates have shown the enormous potential of surface wettability patterns. The ability to fabricate high-contrast wetting patterns on transparent substrates could be of particular interest for lab-on-a-chip devices, sensors, and microfluidics, and thus, it opens up a broad field for further research opportunities.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of Biomimetic Fog-Collecting Superhydrophilic–Superhydrophobic Surface Micropatterns Using Femtosecond Lasers

Kostal¹,

Stroj²,

Kasemann³

et al. 2018

Langmuir

164

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The exciting functionalities of natural superhydrophilic and superhydrophobic surfaces served as inspiration for a variety of biomimetic designs. In particular, the combination of both extreme wetting states to micropatterns opens up interesting applications, as the example of the fog-collecting Namib Desert beetle shows. In this paper, the beetle's elytra were mimicked by a novel three-step fabrication method to increase the fog-collection efficiency of glasses. In the first step, a double-hierarchical surface structure was generated on Pyrex wafers using femtosecond laser structuring, which amplified the intrinsic wetting property of the surface and made it superhydrophilic (water contact angle < 10°). In the second step, a Teflon-like polymer (CF) was deposited by a plasma process that turned the laser-structured surface superhydrophobic (water contact angle> 150°). In the last step, the Teflon-like coating was selectively removed by fs-laser ablation to uncover superhydrophilic spots below the superhydrophobic surface, following the example of the Namib Desert beetle's fog-collecting elytra. To investigate the influence on the fog-collection behavior, (super)hydrophilic, (super)hydrophobic, and low and high contrast wetting patterns were fabricated on glass wafers using selected combinations of these three processing steps and were exposed to fog in an artificial nebulizer setup. This experiment revealed that high-contrast wetting patterns collected the highest amount of fog and enhanced the fog-collection efficiency by nearly 60% compared to pristine Pyrex glass. The comparison of the fog-collection behavior of the six samples showed that the superior fog-collection efficiency of surface patterns with extreme wetting contrast is due to the combination of water attraction and water repellency: the superhydrophilic spots act as drop accumulation areas, whereas the surrounding superhydrophobic areas allow a fast water transportation caused by gravity. The presented method enables a fast and flexible surface functionalization of a broad range of materials including transparent substrates, which offers exciting possibilities for the design of biomedical and microfluidic devices.

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Section: Resultsmentioning

confidence: 99%

Fabrication of Biomimetic Fog-Collecting Superhydrophilic–Superhydrophobic Surface Micropatterns Using Femtosecond Lasers

Kostal¹,

Stroj²,

Kasemann³

et al. 2018

Langmuir

164

View full text Add to dashboard Cite

show abstract

“…The metallic union was grounded with respect to a negatively electrified planar electrode (Trek 610E), and the voltage was 2.1 kV unless otherwise specified (the voltage varied in figure 3). The electrode was made of textured silicon (Zhao et al 2009) to help spread the working fluid, and was held 1 mm apart from the nozzle exit. The flow rate was externally imposed by a syringe pump (KD Scientific 100 or Legato 180).…”

Section: Experimental Methodsmentioning

confidence: 99%

Pulsating electrohydrodynamic cone-jets: from choked jet to oscillating cone

Bober

Chen

2011

J. Fluid Mech.

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Pulsating cone-jets occur in a variety of electrostatic spraying and printing systems. This paper reports an experimental study of the pulsation frequency to reconcile two models based on a choked jet and an oscillating cone, respectively. The two regimes are demarcated by the ratio of the supplied flow rate (${Q}_{s} $) to the minimum flow rate (${Q}_{m} $) required for a steady Taylor cone-jet. When ${Q}_{s} \lesssim {Q}_{m} $, the electrohydrodynamic flow is choked at the nozzle because the intermittent jet, when on, emits mass at the minimum flow rate; the pulsation frequency in the choked jet regime is proportional to ${Q}_{s} / {Q}_{m} $. When ${Q}_{s} \gtrsim {Q}_{m} $, the Taylor cone anchored at the nozzle experiences a capillary oscillation analogous to the Rayleigh mode of a free drop; the pulsation frequency in the oscillating cone regime plateaus to the capillary oscillation frequency, which is independent of ${Q}_{s} / {Q}_{m} $.

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“…The fluid was supplied by a Legato 180 syringe pump to a New Objective PicoTip nozzle with an inner diameter of 100 m and an outer diameter of 150 m. Through a metallic union, the working fluid was electrified between the glass nozzle and a planar counter electrode using a Trek 610E high-voltage amplifier. The counter electrode was made of black silicon [11] to ensure even spreading of the working fluid. Fluid accumulation was further prevented by gravity, which was downward and parallel to the silicon substrate.…”

Section: Methodsmentioning

confidence: 99%

Nonclogging Resistive Pulse Sensing with Electrohydrodynamic Cone-Jet Bridges

2011

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A new paradigm of resistive pulse sensing (Coulter counting) is developed using a liquid bridge in lieu of a solid pore as the sensing aperture, whereby the flexible liquid aperture circumvents the clogging issue of conventional Coulter counters. The electrohydrodynamic bridge is formed between two opposing Taylor cones and stabilized by radial polarization stresses. Passage of a colloidal particle through the upstream conical apex triggers a current oscillation at the resonant frequency of the cone-jet bridge. The relative current change is indicative of the particle-to-jet diameter ratio.

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Beetle Inspired Electrospray Vapor Chamber

Cited by 5 publications

References 9 publications

Fabrication of Biomimetic Fog-Collecting Superhydrophilic–Superhydrophobic Surface Micropatterns Using Femtosecond Lasers

Fabrication of Biomimetic Fog-Collecting Superhydrophilic–Superhydrophobic Surface Micropatterns Using Femtosecond Lasers

Pulsating electrohydrodynamic cone-jets: from choked jet to oscillating cone

Nonclogging Resistive Pulse Sensing with Electrohydrodynamic Cone-Jet Bridges

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