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:

Adaptive liquid microlenses activated by stimuli-responsive hydrogels

Abstract

Despite its compactness, the human eye can easily focus on different distances by adjusting the shape of its lens with the help of ciliary muscles1. In contrast, traditional man-made optical systems achieve focusing by physical displacement of the lenses used. But in recent years, advances in miniaturization technology have led to optical systems that no longer require complicated mechanical systems to tune and adjust optical performance. These systems have found wide use in photonics, displays and biomedical systems. They are either based on arrays of microlenses with fixed focal lengths2,3,4,5, or use external control to adjust the microlens focal length6,7,8,9,10,11,12. An intriguing example is the tunable liquid lens, where electrowetting or external pressure manipulates the shape of a liquid droplet and thereby adjusts its optical properties. Here we demonstrate a liquid lens system that allows for autonomous focusing. The central component is a stimuli-responsive hydrogel13 integrated into a microfluidic system and serving as the container for a liquid droplet, with the hydrogel simultaneously sensing the presence of stimuli and actuating adjustments to the shape—and hence focal length—of the droplet. By working at the micrometre scale where ionic diffusion and surface tension scale favourably14, we can use pinned liquid–liquid interfaces to obtain stable devices and realize response times of ten to a few tens of seconds. The microlenses, which can have a focal length ranging from -∞ to +∞ (divergent and convergent), are also readily integrated into arrays that may find use in applications such as sensing, medical diagnostics and lab-on-a-chip technologies15,16,17,18,19.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

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

Figure 1: Smart microlens using a pinned liquid–liquid interface.
Figure 2: A smart temperature-sensitive liquid microlens using NIPAAm hydrogel.
Figure 3: A smart pH-sensitive liquid microlens using AA hydrogel.
Figure 4: Combination of two smart pH-sensitive liquid microlenses to monitor two areas in space.

Similar content being viewed by others

References

  1. Toates, F. M. Accommodation function of human eye. Physiol. Rev. 52, 828–863 (1972)

    Article  CAS  Google Scholar 

  2. Popovic, Z. D., Sprague, R. A. & Connell, G. A. N. Technique for monolithic fabrication of microlens arrays. Appl. Opt. 27, 1281–1284 (1988)

    Article  ADS  CAS  Google Scholar 

  3. Cayre, O. J. & Paunov, V. N. Fabrication of microlens arrays by gel trapping of self-assembled particle monolayers at the decane-water interface. J. Mater. Chem. 14, 3300–3302 (2004)

    Article  CAS  Google Scholar 

  4. Yang, R., Wang, W. J. & Soper, S. A. Out-of-plane microlens array fabricated using ultraviolet lithography. Appl. Phys. Lett. 86, 161110 (2005)

    Article  ADS  Google Scholar 

  5. Yang, S. et al. Functional biomimetic microlens arrays with integrated pores. Adv. Mater. 17, 435–438 (2005)

    Article  CAS  Google Scholar 

  6. Zhang, D. Y., Lien, V., Berdichevsky, Y., Choi, J. & Lo, Y. H. Fluidic adaptive lens with high focal length tunability. Appl. Phys. Lett. 82, 3171–3172 (2003)

    Article  ADS  CAS  Google Scholar 

  7. Saitoh, A. & Tanaka, K. Self-developing aspherical chalcogenide-glass microlenses for semiconductor lasers. Appl. Phys. Lett. 83, 1725–1727 (2003)

    Article  ADS  CAS  Google Scholar 

  8. Hayes, R. A. & Feenstra, B. J. Video-speed electronic paper based on electrowetting. Nature 425, 383–385 (2003)

    Article  ADS  CAS  Google Scholar 

  9. Kuiper, S. & Hendriks, B. H. W. Variable-focus liquid lens for miniature cameras. Appl. Phys. Lett. 85, 1128–1130 (2004)

    Article  ADS  CAS  Google Scholar 

  10. Ren, H. W., Fan, Y. H. & Wu, S. T. Liquid-crystal microlens arrays using patterned polymer networks. Opt. Lett. 29, 1608–1610 (2004)

    Article  ADS  Google Scholar 

  11. Lopez, C. A., Lee, C. C. & Hirsa, A. H. Electrochemically activated adaptive liquid lens. Appl. Phys. Lett. 87, 134102 (2005)

    Article  ADS  Google Scholar 

  12. Ren, H. & Wu, S. T. Variable-focus liquid lens by changing aperture. Appl. Phys. Lett. 86, 211107 (2005)

    Article  ADS  Google Scholar 

  13. Osada, Y., Gong, J. P. & Tanaka, Y. Polymer gels. J. Macromol. Sci. C 44, 87–112 (2004)

    Article  Google Scholar 

  14. Atencia, J. & Beebe, D. J. Controlled microfluidic interfaces. Nature 437, 648–655 (2005)

    Article  ADS  CAS  Google Scholar 

  15. Camou, S., Fujita, H. & Fujii, T. PDMS 2D optical lens integrated with microfluidic channels: Principle and characterization. Lab Chip 3, 40–45 (2003)

    Article  CAS  Google Scholar 

  16. Chronis, N., Liu, G. L., Jeong, K. H. & Lee, L. P. Tunable liquid-filled microlens array integrated with microfluidic network. Opt. Express 11, 2370–2378 (2003)

    Article  ADS  Google Scholar 

  17. Burns, M. A. et al. An integrated nanoliter DNA analysis device. Science 282, 484–487 (1998)

    Article  ADS  CAS  Google Scholar 

  18. Choi, H. W. et al. GaN micro-light-emitting diode arrays with monolithically integrated sapphire microlenses. Appl. Phys. Lett. 84, 2253–2255 (2004)

    Article  ADS  CAS  Google Scholar 

  19. Carlson, K. et al. In vivo fiber-optic confocal reflectance microscope with an injection-molded plastic miniature objective lens. Appl. Opt. 44, 1792–1797 (2005)

    Article  ADS  Google Scholar 

  20. Park, T. G. & Hoffman, A. S. Synthesis and characterization of pH- and or temperature-sensitive hydrogels. J. Appl. Polym. Sci. 46, 659–671 (1992)

    Article  CAS  Google Scholar 

  21. Suzuki, A. & Tanaka, T. Phase transition in polymer gels induced by visible light. Nature 346, 345–347 (1990)

    Article  ADS  CAS  Google Scholar 

  22. Sershen, S. R. et al. Independent optical control of microfluidic valves formed from optomechanically responsive nanocomposite hydrogels. Adv. Mater. 17, 1366–1368 (2005)

    Article  CAS  Google Scholar 

  23. Tanaka, T., Nishio, I., Sun, S. T. & Uenonishio, S. Collapse of gels in an electric-field. Science 218, 467–469 (1982)

    Article  ADS  CAS  Google Scholar 

  24. Miyata, T., Asami, N. & Uragami, T. A reversibly antigen-responsive hydrogel. Nature 399, 766–769 (1999)

    Article  ADS  CAS  Google Scholar 

  25. Lele, A. K., Hirve, M. M., Badiger, M. V. & Mashelkar, R. A. Predictions of bound water content in poly(N-isopropylacrylamide) gel. Macromolecules 30, 157–159 (1997)

    Article  ADS  CAS  Google Scholar 

  26. Land, M. F. Visual acuity in insects. Annu. Rev. Entomol. 42, 147–177 (1997)

    Article  CAS  Google Scholar 

  27. Jacobs, H. O., Tao, A. R., Schwartz, A., Gracias, D. H. & Whitesides, G. M. Fabrication of a cylindrical display by patterned assembly. Science 296, 323–325 (2002)

    Article  ADS  CAS  Google Scholar 

  28. Beebe, D. J. et al. Functional hydrogel structures for autonomous flow control inside microfluidic channels. Nature 404, 588–590 (2000)

    Article  ADS  CAS  Google Scholar 

  29. Bassetti, M. J., Chatterjee, A. N., Aluru, N. R. & Beebe, D. J. Development and modeling of electrically triggered hydrogels for microfluidic applications. J. Microelectromech. Syst. 14, 1198–1207 (2005)

    Article  Google Scholar 

  30. Agarwal, A. K., Sridharamurthy, S. S., Beebe, D. J. & Jiang, H. Programmable autonomous micromixers and micropumps. J. Microelectromech. Syst. 14, 1409–1421 (2005)

    Article  Google Scholar 

Download references

Acknowledgements

This research was supported in part by the US Department of Homeland Security, through a grant awarded to the National Center for Food Protection and Defense at the University of Minnesota, and in part by the Wisconsin Alumni Research Foundation (WARF). The authors thank J. Moorthy and S.S. Sridharamurthy for discussions.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Hongrui Jiang.

Ethics declarations

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Supplementary information

Supplementary Notes

Smart Microlenses Using Pinned Liquid-Liquid Interfaces (DOC 3282 kb)

Supplementary Video 1 (MOV 1593 kb)

Supplementary Video 2 (MOV 3571 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Dong, L., Agarwal, A., Beebe, D. et al. Adaptive liquid microlenses activated by stimuli-responsive hydrogels. Nature 442, 551–554 (2006). https://doi.org/10.1038/nature05024

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature05024

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

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