Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Condensation on slippery asymmetric bumps

Nature volume 531, pages 78–82 (2016)Cite this article

Subjects

Abstract

Controlling dropwise condensation is fundamental to water-harvesting systems1,2,3, desalination4, thermal power generation4,5,6,7,8, air conditioning9, distillation towers10, and numerous other applications4,5,11. For any of these, it is essential to design surfaces that enable droplets to grow rapidly and to be shed as quickly as possible4,5,6,7. However, approaches4,5,6,7,8,10,11,12,13,14,15,16,17,18,19,20,21 based on microscale, nanoscale or molecular-scale textures suffer from intrinsic trade-offs that make it difficult to optimize both growth and transport at once. Here we present a conceptually different design approach—based on principles derived from Namib desert beetles3,22,23,24, cacti25, and pitcher plants17,26—that synergistically combines these aspects of condensation and substantially outperforms other synthetic surfaces. Inspired by an unconventional interpretation of the role of the beetle’s bumpy surface geometry in promoting condensation, and using theoretical modelling, we show how to maximize vapour diffusion flux20,27,28at the apex of convex millimetric bumps by optimizing the radius of curvature and cross-sectional shape. Integrating this apex geometry with a widening slope, analogous to cactus spines, directly couples facilitated droplet growth with fast directional transport, by creating a free-energy profile that drives the droplet down the slope before its growth rate can decrease. This coupling is further enhanced by a slippery, pitcher-plant-inspired nanocoating that facilitates feedback between coalescence-driven growth and capillary-driven motion on the way down. Bumps that are rationally designed to integrate these mechanisms are able to grow and transport large droplets even against gravity and overcome the effect of an unfavourable temperature gradient. We further observe an unprecedented sixfold-higher exponent of growth rate, faster onset, higher steady-state turnover rate, and a greater volume of water collected compared to other surfaces. We envision that this fundamental understanding and rational design strategy can be applied to a wide range of water-harvesting and phase-change heat-transfer applications.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: An overview of our approach.
Figure 2: Design of, and droplet growth on, convex bumps.
Figure 3: Capillary-driven transport.
Figure 4: Coupled fast growth and transport.

Similar content being viewed by others

References

  1. Clus, O., Ortega, P., Muselli, M., Milimouk, I. & Beysens, D. Study of dew water collection in humid tropical islands. J. Hydrol. 361, 159–171 (2008)

    Google Scholar 

  2. Zheng, Y. et al. Directional water collection on wetted spider silk. Nature 463, 640–643 (2010)

    Google Scholar 

  3. Malik, F. T., Clement, R. M., Gethin, D. T., Krawszik, W. & Parker, A. R. Nature’s moisture harvesters: a comparative review. Bioinspir. Biomim. 9, 031002 (2014)

    Google Scholar 

  4. Miljkovic, N. et al. Jumping-droplet-enhanced condensation on scalable superhydrophobic nanostructured surfaces. Nano Lett. 13, 179–187 (2013)

    Google Scholar 

  5. Rose, J. W. Dropwise condensation theory and experiment: a review. Proc. Inst. Mech. Eng. A 216, 115–128 (2002)

    Google Scholar 

  6. Xiao, R., Miljkovic, N., Enright, R. & Wang, E. N. Immersion condensation on oil-infused heterogeneous surfaces for enhanced heat transfer. Sci. Rep. 3, 1988 (2013)

    Google Scholar 

  7. Anand, S., Paxson, A. T., Dhiman, R., Smith, J. D. & Varanasi, K. K. Enhanced condensation on lubricant-impregnated nanotextured surfaces. ACS Nano 6, 10122–10129 (2012)

    Google Scholar 

  8. Daniel, S., Chaudhurry, M. K. & Chen, J. C. Fast drop movements resulting from the phase change on a gradient surface. Science 291, 633–636 (2001)

    Google Scholar 

  9. Pérez-Lombard, L., Ortiz, J. & Pout, C. A review on buildings energy consumption information. Energy Build. 40, 394–398 (2008)

    Google Scholar 

  10. Rykaczewski, K. et al. Dropwise condensation of low surface tension fluids on omniphobic surfaces. Sci. Rep. 4, 4158 (2014)

    Google Scholar 

  11. Kim, P. et al. Liquid-infused nanostructured surfaces with extreme anti-ice and anti-frost performance. ACS Nano 6, 6569–6577 (2012)

    Google Scholar 

  12. Quéré, D. Wetting and roughness. Annu. Rev. Mater. Res. 38, 71–99 (2008)

    Google Scholar 

  13. Mishchenko, L., Khan, M., Aizenberg, J. & Hatton, B. D. Spatial control of condensation and freezing on superhydrophobic surfaces with hydrophilic patches. Adv. Funct. Mater. 23, 4577–4584 (2013)

    Google Scholar 

  14. Varanasi, K. K., Hsu, M., Bhate, N., Yang, W. & Deng, T. Spatial control in the heterogeneous nucleation of water. Appl. Phys. Lett. 95, 094101 (2009)

    Google Scholar 

  15. Nosonovsky, M. & Bhushan, B. Superhydrophobic surfaces and emerging applications: non-adhesion, energy, green engineering. Curr. Opin. Colloid Interf. Sci. 14, 270–280 (2009)

    Google Scholar 

  16. Courbin, L. et al. Imbibition by polygonal spreading on microdecorated surfaces. Nature Mater. 6, 661–664 (2007)

    Google Scholar 

  17. Wong, T.-S. et al. Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity. Nature 477, 443–447 (2011)

    Google Scholar 

  18. Carlson, A., Kim, P., Amberg, G. & Stone, H. A. Short and long time drop dynamics on lubricated substrates. Europhys. Lett. 104, 34008 (2013)

    Google Scholar 

  19. Krupenkin, T. N., Taylor, J. A., Schneider, T. M. & Yang, S. From rolling ball to complete wetting: the dynamic tuning of liquids on nanostructured surfaces. Langmuir 20, 3824–3827 (2004)

    Google Scholar 

  20. Medici, M.-G., Mongruel, A., Royon, L. & Beysens, D. Edge effects on water droplet condensation. Phys. Rev. E 90, 062403 (2014)

    Google Scholar 

  21. Fratzl, P. & Weinkamer, R. Nature’s hierarchical materials. Prog. Mater. Sci. 52, 1263–1334 (2007)

    Google Scholar 

  22. Parker, A. R. & Lawrence, C. R. Water capture by a desert beetle. Nature 414, 33–34 (2001)

    Google Scholar 

  23. Nørgaard, T. & Dacke, M. Fog-basking behaviour and water collection efficiency in Namib Desert Darkling beetles. Front. Zool. 7, 23 (2010)

    Google Scholar 

  24. Guadarrama-Cetina, J. et al. Dew condensation on desert beetle skin. Eur. Phys. J. E 37, 109 (2014)

    Google Scholar 

  25. Ju, J. et al. A multi-structural and multi-functional integrated fog collection system in cactus. Nature Commun. 3, 1247 (2012)

    Google Scholar 

  26. Bohn, H. F. & Federle, W. Insect aquaplaning: Nepenthes pitcher plants capture prey with the peristome, a fully wettable water-lubricated anisotropic surface. Proc. Natl Acad. Sci. USA 101, 14138–14143 (2004)

    Google Scholar 

  27. Viovy, J. L., Beysens, D. & Knobler, C. M. Scaling description for the growth of condensation patterns on surfaces. Phys. Rev. A 37, 4965–4970 (1988)

    Google Scholar 

  28. Beysens, D. Dew nucleation and growth. C. R. Phys. 7, 1082–1100 (2006)

    Google Scholar 

  29. Zhai, L. et al. Patterned superhydrophobic surfaces: toward a synthetic mimic of the Namib Desert beetle. Nano Lett. 6, 1213–1217 (2006)

    Google Scholar 

  30. Qian, M. & Ma, J. Heterogeneous nucleation on convex spherical substrate surfaces: a rigorous thermodynamic formulation of Fletcher’s classical model and the new perspectives derived. J. Chem. Phys. 130, 214709 (2009)

    Google Scholar 

Download references

Acknowledgements

We thank M. Khan, J. Alvarenga, D. Daniel, S. H. Kang, M. Hoang, and J. Timonen for discussions and technical assistance. This research was supported by the Department of Energy/ARPA-E award number DE-AR0000326. N.H. thanks the Research Experiences for Undergraduates programme supported by the National Science Foundation award number DMR-1420570.

Author information

Authors and Affiliations

  1. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA

    Kyoo-Chul Park, Alison Grinthal, Neil He, David Fox & Joanna Aizenberg

  2. Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, USA

    Kyoo-Chul Park, Philseok Kim, James C. Weaver & Joanna Aizenberg

  3. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, USA

    Joanna Aizenberg

Authors
  1. Kyoo-Chul Park
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Philseok Kim
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Alison Grinthal
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Neil He
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. David Fox
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. James C. Weaver
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Joanna Aizenberg
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

K.-C.P., P.K. and J.A. conceived the research. J.A. supervised the research. K.-C.P., P.K. and J.A. designed the slippery asymmetric bumps and the experiments. K.-C.P., P.K., N.H., D.F. and J.C.W. carried out the experiments. All authors analysed data. K.-C.P. built the analytical and numerical models. K.-C.P., P.K., A.G., D.F. and J.A. interpreted data and wrote the paper.

Corresponding authors

Correspondence to Kyoo-Chul Park or Joanna Aizenberg.

Ethics declarations

Competing interests

J.A. and P.K. are founders of the start-up company SLIPS Technologies, Inc.

Supplementary information

Supplementary Information

This file contains Supplementary Text and Data, Supplementary Tables 1-3 Supplementary Figures 1-10 and Supplementary references – see contents for details. (PDF 2349 kb)

Fast droplet growth on a PDMS-coated spherical-cap-shaped bump compared to a flat region with the same height

This video demonstrates the fast droplet growth on a PDMS-coated spherical-cap-shaped bump (left) compared to a flat region with the same height (right). The diameter of the largest droplet on the apex of the bump is greater than that of a droplet on the flat region. This video corresponds to Fig. 2b of the main text. (MOV 2687 kb)

Bump without additional roughening by sandpaper still exhibits greater droplets on its apex compared to roughened flat surfaces with the same height

This video demonstrates that the bump without additional roughening by sandpaper still exhibits greater droplets on its apex compared to the roughened flat surfaces with the same height, thus ruling out the importance of the micro/nano surface roughness to the observed preferential droplet growth at the apex of the structures. This video corresponds to Supplementary Fig. S3. (MOV 3923 kb)

Condensed water droplets moving against gravity on an asymmetric bump

This video demonstrates that condensed water droplets move even against gravity on an asymmetric bump. The droplet moves toward the wider flat area of the slope such that it no longer overlaps with the curved regions and further grows by coalescing with the smaller droplets on the way. This video corresponds to Fig. 3d of the main text. (MOV 4376 kb)

Condensed water droplets move down the widening slope of the slippery asymmetric bumps when the slope is tilted 45 or 90 degrees relative to gravity

This video demonstrates that condensed water droplets move down the widening slope of the slippery asymmetric bumps when the slope is tilted 45 (left) or 90 degrees (right) relative to gravity. In both cases, the droplet moves toward the wider flat area of the slope such that it no longer overlaps with the curved regions and further grows by coalescing with the smaller droplets on the way, similar to Supplementary Video 3. This video corresponds to Fig. 3e of the main text. (MOV 1461 kb)

Condensed water droplets do not show directed transport on slippery bumps that have a rectangular, rather than an asymmetric widening, slope.

This video demonstrates that condensed water droplets do not show directed transport on slippery bumps that have a rectangular, rather than an asymmetric widening, slope. Without the asymmetry, the droplets fall off the side of the bump and slide next to it in the direction of gravity, whether the bump slope is aligned with (left) or against (right) gravity. (MOV 5214 kb)

Exemplary array of the slippery asymmetric bumps shows a significantly greater volume of water collected at the bottom of the surface, compared to the flat slippery surfaces.

This video demonstrates that an exemplary array of the slippery asymmetric bumps (left) shows a significantly greater volume of water collected at the bottom of the surface, compared to the flat slippery surfaces (right). This video corresponds to Fig. 4c of the main text and Supplementary Fig. S9. (MOV 5705 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Park, KC., Kim, P., Grinthal, A. et al. Condensation on slippery asymmetric bumps. Nature 531, 78–82 (2016). https://doi.org/10.1038/nature16956

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature16956

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing