Self-Propelled Detachment upon Coalescence of Surface Bubbles

Lv, Pengyu; Peñas, Pablo; Le‐The, Hai; Eijkel, Jan C.T.; Berg, Albert van den; Zhang, Xuehua; Lohse, Detlef

doi:10.1103/physrevlett.127.235501

Cited by 33 publications

(37 citation statements)

References 50 publications

(53 reference statements)

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“…This behaviour falls under the sticking bubble regime in the literature, a phenomenon long observed in experiments [63,64] but only recently thoroughly studied and theorized in a catalytic H 2 O 2 bubble system [65]. Importantly, contrary to the more intuitive moving bubble regime where the merged bubble sits at the centre of mass of its parents [66,67], the coalescence behaviour transitions into the sticking regime only as the parent bubbles differ sufficiently in size [65], or, in other words, with sufficient particle heterogeneity. As shown in the rest of Figs.…”

Section: Persistent Periodicity Via Symmetry-breakingmentioning

confidence: 63%

Emergent Microrobotic Oscillators via Asymmetry-Induced Order

Yang¹,

Berrueta²,

Brooks³

et al. 2022

Preprint

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Spontaneous low-frequency oscillations on the order of several hertz are the drivers of many crucial processes in nature [1][2][3][4]. From bacterial swimming [5, 6] to mammal gaits [7, 8], the conversion of static energy inputs into slowly oscillating electrical and mechanical power is key to the autonomy of organisms across scales [9][10][11][12]. However, the fabrication of slow artificial oscillators at micrometre scales remains a major roadblock [13][14][15][16] towards the development of fully-autonomous microrobots [17][18][19][20]. Here, we report the emergence of a lowfrequency relaxation oscillator from a simple collective of active microparticles interacting at the air-liquid interface of a hydrogen peroxide drop. Their collective oscillations form chemomechanical [21] and electrochemical [22] limit cycles that enable the transduction of ambient chemical energy into periodic mechanical motion and on-board electrical currents. Surprisingly, the collective can oscillate robustly even as more particles are introduced, but only when we add a single particle with modified reactivity to intentionally break the system's permutation symmetry [23]. We explain such emergent order through a novel thermodynamic mechanism for asymmetry-induced order [24, 25]. The energy harvested from the stabilized oscillations enables the use of on-board electronic components, which we demonstrate by cyclically and synchronously driving a microrobotic arm [26][27][28]. This work highlights a new strategy for achieving low-frequency oscillations at the microscale that are otherwise difficult to observe outside of natural systems, paving the way for future microrobotic autonomy.

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Section: Persistent Periodicity Via Symmetry-breakingmentioning

confidence: 63%

Emergent Microrobotic Oscillators via Asymmetry-Induced Order

Yang¹,

Berrueta²,

Brooks³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…36 More quantitative study of bubble coalescence and bubble detachment on the solid surface was reported in previous work. 42 For multiple bubbles in a droplet, bubbles around the droplet rim grew faster than those near the droplet center. For example, from t =15 s to t =97 s in Figure 3A&B, bubbles at the droplet rim became ∼ 40% larger in base radius, while bubbles far from the droplet rim remained almost the same size.…”

Section: Growing Microbubbles In Reacting Surface Dropletmentioning

confidence: 99%

Growth Rates of Hydrogen Microbubbles in Reacting Femtoliter Droplets

Li¹,

Zeng²,

Zhang³

2022

Preprint

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Chemical reactions in small droplets are extensively explored to accelerate the discovery of new materials, increase efficiency and specificity in catalytic biphasic conversion and in high throughput analytic. In this work, we investigate the local rate of gas-evolution reaction within femtoliter droplets immobilized on a solid surface. The growth rate of hydrogen microbubbles (≥ 500 nm in radius) produced from the reaction was measured online by high-resolution confocal microscopic images. The growth rate of bubbles was faster in smaller droplets, and of bubbles near the three-phase boundary in the same droplet. The results were consistent for both pure and binary reacting droplets and on substrates of different wettability. Our theoretical analysis based on diffusion, chemical reaction and bubble growth in a steady state predicted that the concentration of the reactant diffusing from the surrounding depended on the droplet size and the bubble location inside the droplet, in good agreement with experimental results. Our results reveal that the reaction rate may be spatially non-uniform in the reacting microdroplets. The findings may have implications for formulating chemical properties and uses of these droplets.

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“…The motion of bubbles on a partially wetting substrate is important in application and includes, for example, bubble detachment in nucleate boiling for heat transfer (Douglas et al 2012;Pereiro et al 2019;Ardron & Giustini 2021), bubble collapse that affects solder joint quality in ultrasonic-assisted soldering (Shaffer et al 2019;Maassen et al 2020), bubble detachment via coalescence in catalytic or electrochemical gas evolution reactions in liquids (Lv et al 2021), microstreaming from oscillating bubbles in micro-electromechanical systems (Marmottant et al 2006), bubble generation on biological matter (Kawchuk et al 2015), and the sound generated by the collapse of a rising bubble at the surface of a lava column (Vergniolle & Brandeis 1996). Here, the bubble dynamics may involve translation (detachment), volume change (collapse or growth), liquid/gas surface shape change (oscillations), or some combination thereof, and these are often affected by the wetting conditions on the solid substrate.…”

Section: Introductionmentioning

confidence: 99%

“…2020), bubble detachment via coalescence in catalytic or electrochemical gas evolution reactions in liquids (Lv et al. 2021), microstreaming from oscillating bubbles in micro-electromechanical systems (Marmottant et al. 2006), bubble generation on biological matter (Kawchuk et al.…”

Section: Introductionmentioning

confidence: 99%

Oscillations of a partially wetting bubble

Ding

Bostwick

2022

J. Fluid Mech.

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We study the linear stability of a compressible sessile bubble in an ambient fluid that partially wets a planar solid support, where the gas is assumed to be an ideal gas that obeys the adiabatic law. The frequency spectrum is computed from an integrodifferential boundary value problem and depends upon the wetting conditions through the static contact angle $\alpha$ , the dimensionless equilibrium bubble pressure $\varPi$ , and the contact-line dynamics that we assume to be either (i) pinned or (ii) freely moving with fixed contact angle. Corresponding mode shapes are defined by the polar-azimuthal mode number pair $[k,\ell ]$ with $k+\ell =\mathbb {Z}^{+}_{even}$ . We report instabilities to the (i) $[0,0]$ breathing mode associated with volume change, and (ii) $[1,1]$ mode that is linked to horizontal centre-of-mass motion of the bubble. Stability diagrams and instability growth rates are computed, and the respective instability mechanisms are revealed through an energy analysis. The zonal $\ell =0$ modes are associated with volume change, and we show that there is a complex dependence between the classical volume and shape change modes for wetting conditions that differ from neutral wetting $\alpha =90^\circ$ . Finally, we show how the classical frequency degeneracy for the Rayleigh–Lamb modes of the free bubble splits for the azimuthal modes $\ell \neq 0,1$ .

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Self-Propelled Detachment upon Coalescence of Surface Bubbles

Cited by 33 publications

References 50 publications

Emergent Microrobotic Oscillators via Asymmetry-Induced Order

Emergent Microrobotic Oscillators via Asymmetry-Induced Order

Growth Rates of Hydrogen Microbubbles in Reacting Femtoliter Droplets

Oscillations of a partially wetting bubble

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