Abstract

A microfluidic device that operates as a set of two adaptive cylindrical lenses focusing light along two orthogonal axes is designed, fabricated and characterized. The device is made out of a silicon elastomer, polydimethylsiloxane, using soft lithography, and consists of a few chambers separated by flexible membranes and filled with liquids of different refractive indices. The cylindrical lenses can be both converging and diverging; their focal lengths are varied independently and continuously adjusted between -40 and 23 mm by setting pressure in the chambers. Applications of the device to shaping of a laser beam, imaging and optical signal processing are demonstrated.

© 2005 Optical Society of America

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References

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  1. D. W. Berreman, US Patent No. 4,190,330 (1980).
  2. S. Sato, "Liquid-crystal lens-cells with variable focal length," Japanese J. of Appl. Phys. 18, 1679-1684 (1979).
    [CrossRef]
  3. A. F. Naumov, M. Y. Loktev, I. R. Guralnik, and G. Vdovin, "Liquid-crystal adaptive lenses with modal control," Opt. Lett. 23, 992-994 (1998).
    [CrossRef]
  4. L. G. Commander, S. E. Day, and D. R. Selviah, "Variable focal length microlenses," Opt. Commun. 177, 157-170 (2000).
    [CrossRef]
  5. T. Krupenkin, S. Yang, and P. Mach, "Tunable liquid microlens," Appl. Phys. Lett. 82, 316-318 (2003).
    [CrossRef]
  6. S. Kuiper and B. H. W. Hendriks, "Variable-focus liquid lens for miniature cameras" Appl. Phys. Lett. 85, 1128-1130 (2004).
    [CrossRef]
  7. B. M. Wright, UK Patent No. 1,209,234 (1968).
  8. G. C. Knollman, J. L. S. Bellin, and J. L. Weaver, "Variable-focus liquid filled hydroacoustic lens," J. Acous. Soc. Am. 49, 253 (1971).
    [CrossRef]
  9. D. Y. Zhang, V. Lien, Y. Berdichevsky, J. Choi, and Y. H. Lo, "Fluidic adaptive lens with high focal length tunability," Appl. Phys. Lett. 82, 3171-3173 (2003).
    [CrossRef]
  10. D. Y. Zhang, N. Justis, V. Lien, Y. Berdichevsky, and Y. H. Lo, "High-performance fluidic adaptive lenses," Appl. Opt. 43, 783-787 (2004).
    [CrossRef] [PubMed]
  11. D. Y. Zhang, N. Justis, and Y. H. Lo, D. Y. Zhang, N. Justis, and Y. H. Lo, "Fluidic adaptive lens of transformable lens type," Appl. Phys. Lett. 84, 4194-4196 (2004).," Appl. Phys. Lett. 84, 4194-4196 (2004).
    [CrossRef]
  12. N. Chronis, G. L. Liu, K. H. Jeong, and L. P. Lee, "Tunable liquid-filled microlens array integrated with microfluidic network," Opt. Express 11, 2370-2378 (2003).
    [CrossRef] [PubMed]
  13. Y. N. Xia and G. M. Whitesides, "Soft lithography," Angewandte Chemie-International Edition 37, 550-575 (1998).
    [CrossRef]
  14. H. Schmid and B. Michel, "Siloxane polymers for high-resolution, high-accuracy soft lithography," Macromolecules 33, 3042-3049 (2000).
    [CrossRef]
  15. M. A. Unger, H. P. Chou, T. Thorsen, A. Scherer, and S. R. Quake, "Monolithic microfabricated valves and pumps by multilayer Soft lithography," Science 288, 113-116 (2000).
    [CrossRef]
  16. A. Groisman, M. Enzelberger, and S.R. Quake, "Microfluidic memory and control devices," Science 300, 955-958 (2003).
    [CrossRef] [PubMed]

Angewandte Chemie-International Edition (1)

Y. N. Xia and G. M. Whitesides, "Soft lithography," Angewandte Chemie-International Edition 37, 550-575 (1998).
[CrossRef]

Appl. Opt. (1)

Appl. Phys. Lett. (4)

T. Krupenkin, S. Yang, and P. Mach, "Tunable liquid microlens," Appl. Phys. Lett. 82, 316-318 (2003).
[CrossRef]

S. Kuiper and B. H. W. Hendriks, "Variable-focus liquid lens for miniature cameras" Appl. Phys. Lett. 85, 1128-1130 (2004).
[CrossRef]

D. Y. Zhang, V. Lien, Y. Berdichevsky, J. Choi, and Y. H. Lo, "Fluidic adaptive lens with high focal length tunability," Appl. Phys. Lett. 82, 3171-3173 (2003).
[CrossRef]

D. Y. Zhang, N. Justis, and Y. H. Lo, D. Y. Zhang, N. Justis, and Y. H. Lo, "Fluidic adaptive lens of transformable lens type," Appl. Phys. Lett. 84, 4194-4196 (2004).," Appl. Phys. Lett. 84, 4194-4196 (2004).
[CrossRef]

J. Acous. Soc. Am. (1)

G. C. Knollman, J. L. S. Bellin, and J. L. Weaver, "Variable-focus liquid filled hydroacoustic lens," J. Acous. Soc. Am. 49, 253 (1971).
[CrossRef]

Japanese J. of Appl. Phys. (1)

S. Sato, "Liquid-crystal lens-cells with variable focal length," Japanese J. of Appl. Phys. 18, 1679-1684 (1979).
[CrossRef]

Macromolecules (1)

H. Schmid and B. Michel, "Siloxane polymers for high-resolution, high-accuracy soft lithography," Macromolecules 33, 3042-3049 (2000).
[CrossRef]

Opt. Commun. (1)

L. G. Commander, S. E. Day, and D. R. Selviah, "Variable focal length microlenses," Opt. Commun. 177, 157-170 (2000).
[CrossRef]

Opt. Express (1)

Opt. Lett. (1)

Science (2)

M. A. Unger, H. P. Chou, T. Thorsen, A. Scherer, and S. R. Quake, "Monolithic microfabricated valves and pumps by multilayer Soft lithography," Science 288, 113-116 (2000).
[CrossRef]

A. Groisman, M. Enzelberger, and S.R. Quake, "Microfluidic memory and control devices," Science 300, 955-958 (2003).
[CrossRef] [PubMed]

Other (2)

B. M. Wright, UK Patent No. 1,209,234 (1968).

D. W. Berreman, US Patent No. 4,190,330 (1980).

Supplementary Material (2)

» Media 1: MPG (395 KB)     
» Media 2: MPG (1802 KB)     

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Figures (6)

Fig. 1.
Fig. 1.

(a) A schematic drawing of the device, demonstrating its operation as a positive cylindrical lens along the y-axis and a negative cylindrical lens along the x-axis. Numbers and letters A and B designate chambers (and layers) and membranes, respectively. The low refractive index liquid in chambers 1 and 4 is shown as yellow, and the high refractive index liquid in chambers 2 and 3 is shown as blue. (b) A micrograph of the fabricated device. Three inlets are connected to chambers 1, 2–3 and 4.

Fig. 2.
Fig. 2.

Schematic drawing showing consecutive steps of the device fabrication. (a) The master mold defining chamber 1 with the PDMS cast on the top. (b) The PDMS chip with chamber 1 is aligned on top of the master mold that defines chamber 2 and is spin-coated with a thin layer of PDMS. (c) Two parts of the device with chambers 1 and 2 (top) and 3 and 4 (bottom) are brought into a contact and bonded.

Fig. 3.
Fig. 3.

Focal lengths of the cylindrical lenses focusing light along the x-axis (squares) and y-axis (crosses) as functions of the pressure differences, ΔPx and ΔPy , respectively.

Fig. 4.
Fig. 4.

Intensity profiles of a laser beam focused at 32 mm from the device and captured by a CCD camera in the focal plane: (a) along the x-axis and (b) along the y-axis. Inset in (a): a fragment of read-out of the CCD camera.

Fig. 5.
Fig. 5.

Demonstration of the laser mode shaping with a CCD camera placed at z = 200 mm behind the device. The driving pressures are: (a–c) ΔPx = ΔPy = 1.2 kPa; (d–f) ΔPx = 1.2 kPa, ΔPy = 0.8 kPa; (g–i) ΔPx = 0.8 kPa, ΔPy = 1.2 kPa. The panels (a), (d) and (g) show patterns of light on the CCD. The panels (b), (e) and (h) show intensity profiles in the x-direction (along a line going through the center of the laser spot), and the panels (c), (f) and (i) show intensity profiles in the y-direction. The intensity profiles in (b) and (e), (c) and (i) are nearly identical that implies practically no cross-talk between the two lenses. Movie (started by a click on (a)) shows the transition between (a) and (g) after ΔPx is switched from 1.2 kPa to 0.8 kPa. [Media 1]

Fig. 6.
Fig. 6.

Demonstration of imaging and optical signal processing. (a) Image of a target taken under a microscope; (b) image of the target projected on the CCD by the device at 2f = l 1 = l 2 ; (c) Fourier transform of the target (diffraction pattern) projected on the CCD at f =l 2 . [Media 2]

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