Optimal free-surface pumping by an undulating carpet

Pandey, Anupam; Chen, Zih-Yin; Yuk, Jisoo; Sun, Yuming; Roh, Chris; Takagi, Daisuke; Lee, Sungyon; Jung, Sunghwan

doi:10.1038/s41467-023-43059-8

Cited by 7 publications

References 43 publications

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Wireless Peristaltic Pump for Transporting Viscous Fluids and Solid Cargos in Confined Spaces

Sharma,

Jung,

Lee

et al. 2024

Adv Funct Materials

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The transport of fluids and solids is a vital process inside the human body, facilitated by the wave‐like motion in the lumen called peristalsis. However, peristalsis may be compromised due to tumor growth, resulting in difficulties in lumen motility. The dysmotility of the human lumen can result in blockages and pose numerous challenges, including aspiration in the lungs and reproductive issues in the female oviduct. Restoring peristalsis in medical devices, such as medical stents, can prevent device blockage and promote effective transport. Here, a wirelessly actuated soft robotic undulating pump designed to efficiently transport both viscous fluidic and solid cargos is proposed. The kinematics of the single sheet and the coordination between pairs are systematically designed to generate undulation and peristalsis, enabling the pumping of both liquids and solids. The integration of the undulating pump is demonstrated onto an esophageal stent. The same undulating motion‐based pumping mechanism can be adapted for usage in other organs, such as the female oviduct, thereby offering potential applications for treating lumen dysmotility in various diseases. The proposed wirelessly actuated robotic pumping mechanism holds promise in facilitating diverse implantable medical devices aimed at treating diseases characterized by impaired peristalsis and dysmotility.

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Wireless Peristaltic Pump for Transporting Viscous Fluids and Solid Cargos in Confined Spaces

Sharma,

Jung,

Lee

et al. 2024

Adv Funct Materials

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Capillary Skimming of Floating Microplastics via a Water‐Bridged Ratchet

Cho,

Park,

Lee

et al. 2024

Advanced Science

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Floating microplastics (MPs) have recently become a major concern in marine pollution; however, current filter‐based technology is hardly effective for directly removing such MPs from the water surface because of specific mesh size and clogging issues. This paper introduces a new skimming concept for removing floating MPs utilizing capillary force mediated by the elevation of a hydrophilic ratchet at the air−water interface. MPs floating near the ratchet surface are spontaneously forced toward the ratchet with a concave water meniscus, driven by the Cheerios effect. The MPs can then be skimmed and temporarily held by the deforming concave water meniscus as the ratchet rises. Here, it is found that the stability of the water bridge plays a crucial role in skimming success because it provides capillary adhesion between the MP and the ratchet. The proposed capillary skimming method is observed to be effective across nearly all types of floating MPs, ranging in size from 1 to 4 mm, and with densities varying from 0.02 to 0.97 g cm−3, which is also demonstrated by a prototype of marine robot cleaner.

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Inertial effects on free surface pumping with an undulating surface

Chen,

Pandey,

Takagi

et al. 2024

J. Fluid Mech.

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Free surface flows driven by boundary undulations are observed in many biological phenomena, including the feeding and locomotion of water snails. To simulate the feeding strategy of apple snails, we develop a centimetric robotic undulator that drives a thin viscous film of liquid with the wave speed $V_w$ . Our experimental results demonstrate that the behaviour of the net fluid flux $Q$ strongly depends on the Reynolds number $Re$ . Specifically, in the limit of vanishing $Re$ , we observe that $Q$ varies non-monotonically with $V_w$ , which has been successfully rationalised by Pandey et al. (Nat. Commun., vol. 14, no. 1, 2023, p. 7735) with the lubrication model. By contrast, in the regime of finite inertia ( ${Re} \sim O(1)$ ), the fluid flux continues to increase with $V_w$ and completely deviates from the prediction of lubrication theory. To explain the inertia-enhanced pumping rate, we build a thin-film, two-dimensional model via the asymptotic expansion in which we linearise the effects of inertia. Our model results match the experimental data with no fitting parameters and also show the connection to the corresponding free surface shapes $h_2$ . Going beyond the experimental data, we derive analytical expressions of $Q$ and $h_2$ , which allow us to decouple the effects of inertia, gravity, viscosity and surface tension on free surface pumping over a wide range of parameter space.

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Optimal free-surface pumping by an undulating carpet

Cited by 7 publications

References 43 publications

Wireless Peristaltic Pump for Transporting Viscous Fluids and Solid Cargos in Confined Spaces

Wireless Peristaltic Pump for Transporting Viscous Fluids and Solid Cargos in Confined Spaces

Capillary Skimming of Floating Microplastics via a Water‐Bridged Ratchet

Inertial effects on free surface pumping with an undulating surface

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