Abstract

A liquid crystal droplet lens driven by the dielectrophoresis (DEP) force was demonstrated. The liquid crystal droplet lens was deformed by the DEP forces under non-uniform AC electric fields. Focal length, hysteresis and electrode design were studied. The focal length varied from 1.6mm to 2.6mm in the range of 0-200V at 1 kHz for electrode spacing of 50μm; that is, the tuning ratio of the focal length was about 60% in maximum. The hysteresis of contact angle was found to be less than 3° and it vanished after 1 minute at the rest state. As the electrode spacing over 200μm, the tuning ratios of the focal length dropped below 5%. The liquid crystal droplet lens that had numerical aperture of about 0.5 consumed power of about 0.1mW. Its response time was measured to be about 220ms.

© 2006 Optical Society of America

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References

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  1. T. Nose, S Masuda and S Sato, "A liquid crystal microlens with hole-patterned electrodes on both substrates," Jpn. J. Appl. Phys. 31, 1643 (1992)
    [CrossRef]
  2. Y. Choi, J.-H. Park, J.-H Kim, and S.-D. Lee, "Fabrication of a focal length variable microlens array based on a nematic liquid crystal," Opt. Mater. 21, 643 (2003)
    [CrossRef]
  3. H Ren, Y H Fan and S T Wu, "Liquid-crystal microlens arrays using patterned polymer networks," Opt. Lett. 29, 1608 (2004).
    [CrossRef] [PubMed]
  4. B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159 (2000).
    [CrossRef]
  5. S. Kwon and L. P. Lee, "Focal length control by microfabricated planar electrodes-based liquid lens (μPELL)," Transducers Eurosensors, Germany, 10-14 June, (2001)
  6. 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 (2003)
    [CrossRef] [PubMed]
  7. M. Agarwal, R. A. Gunasekaran, P. Coane and K. Varahramyan, "Polymer-based variable focal length microlens system," J. Micromech. Microeng. 14, 1665 (2004)
    [CrossRef]
  8. F. Mugele and J-C Baret, "Electrowetting: from basics to applications," J. Phys.: Condens. Matter 17, R705 (2005)
    [CrossRef]
  9. E. Seyrat and R. A. Hayes, "Amorphous fluoropolymers as insulators for reversible low-voltage electrowetting," J. Appl. Phys. 90, 1383 (2001)
    [CrossRef]
  10. T. B. Jones, M. Gunji, M. Washizu, and M. J. Feldman, "Dielectrophoretic liquid actuation and nanodroplet formation," J. Appl. Phys. 89, 1441 (2001)
    [CrossRef]
  11. T. B. Jones, "Liquid dielectrophoresis on the microscale," J. Electrost. 51-52, 290 (2001)
    [CrossRef]
  12. S. Kwon and L. P. Lee, "Focal length control by microfabricated planar electrodes-based liquid lens (μPELL)," Transducers Eurosensors, Germany, 10-14 June, (2001)

2005 (1)

F. Mugele and J-C Baret, "Electrowetting: from basics to applications," J. Phys.: Condens. Matter 17, R705 (2005)
[CrossRef]

2004 (2)

M. Agarwal, R. A. Gunasekaran, P. Coane and K. Varahramyan, "Polymer-based variable focal length microlens system," J. Micromech. Microeng. 14, 1665 (2004)
[CrossRef]

H Ren, Y H Fan and S T Wu, "Liquid-crystal microlens arrays using patterned polymer networks," Opt. Lett. 29, 1608 (2004).
[CrossRef] [PubMed]

2003 (2)

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 (2003)
[CrossRef] [PubMed]

Y. Choi, J.-H. Park, J.-H Kim, and S.-D. Lee, "Fabrication of a focal length variable microlens array based on a nematic liquid crystal," Opt. Mater. 21, 643 (2003)
[CrossRef]

2001 (3)

E. Seyrat and R. A. Hayes, "Amorphous fluoropolymers as insulators for reversible low-voltage electrowetting," J. Appl. Phys. 90, 1383 (2001)
[CrossRef]

T. B. Jones, M. Gunji, M. Washizu, and M. J. Feldman, "Dielectrophoretic liquid actuation and nanodroplet formation," J. Appl. Phys. 89, 1441 (2001)
[CrossRef]

T. B. Jones, "Liquid dielectrophoresis on the microscale," J. Electrost. 51-52, 290 (2001)
[CrossRef]

2000 (1)

B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159 (2000).
[CrossRef]

1992 (1)

T. Nose, S Masuda and S Sato, "A liquid crystal microlens with hole-patterned electrodes on both substrates," Jpn. J. Appl. Phys. 31, 1643 (1992)
[CrossRef]

Agarwal, M.

M. Agarwal, R. A. Gunasekaran, P. Coane and K. Varahramyan, "Polymer-based variable focal length microlens system," J. Micromech. Microeng. 14, 1665 (2004)
[CrossRef]

Baret, J-C

F. Mugele and J-C Baret, "Electrowetting: from basics to applications," J. Phys.: Condens. Matter 17, R705 (2005)
[CrossRef]

Berge, B.

B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159 (2000).
[CrossRef]

Choi, Y.

Y. Choi, J.-H. Park, J.-H Kim, and S.-D. Lee, "Fabrication of a focal length variable microlens array based on a nematic liquid crystal," Opt. Mater. 21, 643 (2003)
[CrossRef]

Chronis, N.

Coane, P.

M. Agarwal, R. A. Gunasekaran, P. Coane and K. Varahramyan, "Polymer-based variable focal length microlens system," J. Micromech. Microeng. 14, 1665 (2004)
[CrossRef]

Fan, Y H

Feldman, M. J.

T. B. Jones, M. Gunji, M. Washizu, and M. J. Feldman, "Dielectrophoretic liquid actuation and nanodroplet formation," J. Appl. Phys. 89, 1441 (2001)
[CrossRef]

Gunasekaran, R. A.

M. Agarwal, R. A. Gunasekaran, P. Coane and K. Varahramyan, "Polymer-based variable focal length microlens system," J. Micromech. Microeng. 14, 1665 (2004)
[CrossRef]

Gunji, M.

T. B. Jones, M. Gunji, M. Washizu, and M. J. Feldman, "Dielectrophoretic liquid actuation and nanodroplet formation," J. Appl. Phys. 89, 1441 (2001)
[CrossRef]

Hayes, R. A.

E. Seyrat and R. A. Hayes, "Amorphous fluoropolymers as insulators for reversible low-voltage electrowetting," J. Appl. Phys. 90, 1383 (2001)
[CrossRef]

Jeong, K-H

Jones, T. B.

T. B. Jones, "Liquid dielectrophoresis on the microscale," J. Electrost. 51-52, 290 (2001)
[CrossRef]

T. B. Jones, M. Gunji, M. Washizu, and M. J. Feldman, "Dielectrophoretic liquid actuation and nanodroplet formation," J. Appl. Phys. 89, 1441 (2001)
[CrossRef]

Kim, J.-H

Y. Choi, J.-H. Park, J.-H Kim, and S.-D. Lee, "Fabrication of a focal length variable microlens array based on a nematic liquid crystal," Opt. Mater. 21, 643 (2003)
[CrossRef]

Lee, L. P.

Lee, S.-D.

Y. Choi, J.-H. Park, J.-H Kim, and S.-D. Lee, "Fabrication of a focal length variable microlens array based on a nematic liquid crystal," Opt. Mater. 21, 643 (2003)
[CrossRef]

Liu, G. L.

Masuda, S

T. Nose, S Masuda and S Sato, "A liquid crystal microlens with hole-patterned electrodes on both substrates," Jpn. J. Appl. Phys. 31, 1643 (1992)
[CrossRef]

Mugele, F.

F. Mugele and J-C Baret, "Electrowetting: from basics to applications," J. Phys.: Condens. Matter 17, R705 (2005)
[CrossRef]

Nose, T.

T. Nose, S Masuda and S Sato, "A liquid crystal microlens with hole-patterned electrodes on both substrates," Jpn. J. Appl. Phys. 31, 1643 (1992)
[CrossRef]

Park, J.-H.

Y. Choi, J.-H. Park, J.-H Kim, and S.-D. Lee, "Fabrication of a focal length variable microlens array based on a nematic liquid crystal," Opt. Mater. 21, 643 (2003)
[CrossRef]

Peseux, J.

B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159 (2000).
[CrossRef]

Ren, H

Sato, S

T. Nose, S Masuda and S Sato, "A liquid crystal microlens with hole-patterned electrodes on both substrates," Jpn. J. Appl. Phys. 31, 1643 (1992)
[CrossRef]

Seyrat, E.

E. Seyrat and R. A. Hayes, "Amorphous fluoropolymers as insulators for reversible low-voltage electrowetting," J. Appl. Phys. 90, 1383 (2001)
[CrossRef]

Varahramyan, K.

M. Agarwal, R. A. Gunasekaran, P. Coane and K. Varahramyan, "Polymer-based variable focal length microlens system," J. Micromech. Microeng. 14, 1665 (2004)
[CrossRef]

Washizu, M.

T. B. Jones, M. Gunji, M. Washizu, and M. J. Feldman, "Dielectrophoretic liquid actuation and nanodroplet formation," J. Appl. Phys. 89, 1441 (2001)
[CrossRef]

Wu, S T

Eur. Phys. J. E (1)

B. Berge and J. Peseux, "Variable focal lens controlled by an external voltage: An application of electrowetting," Eur. Phys. J. E 3, 159 (2000).
[CrossRef]

J. Appl. Phys. (2)

E. Seyrat and R. A. Hayes, "Amorphous fluoropolymers as insulators for reversible low-voltage electrowetting," J. Appl. Phys. 90, 1383 (2001)
[CrossRef]

T. B. Jones, M. Gunji, M. Washizu, and M. J. Feldman, "Dielectrophoretic liquid actuation and nanodroplet formation," J. Appl. Phys. 89, 1441 (2001)
[CrossRef]

J. Electrost. (1)

T. B. Jones, "Liquid dielectrophoresis on the microscale," J. Electrost. 51-52, 290 (2001)
[CrossRef]

J. Micromech. Microeng. (1)

M. Agarwal, R. A. Gunasekaran, P. Coane and K. Varahramyan, "Polymer-based variable focal length microlens system," J. Micromech. Microeng. 14, 1665 (2004)
[CrossRef]

J. Phys.: Condens. Matter (1)

F. Mugele and J-C Baret, "Electrowetting: from basics to applications," J. Phys.: Condens. Matter 17, R705 (2005)
[CrossRef]

Jpn. J. Appl. Phys. (1)

T. Nose, S Masuda and S Sato, "A liquid crystal microlens with hole-patterned electrodes on both substrates," Jpn. J. Appl. Phys. 31, 1643 (1992)
[CrossRef]

Opt. Express (1)

Opt. Lett. (1)

Opt. Mater. (1)

Y. Choi, J.-H. Park, J.-H Kim, and S.-D. Lee, "Fabrication of a focal length variable microlens array based on a nematic liquid crystal," Opt. Mater. 21, 643 (2003)
[CrossRef]

Other (2)

S. Kwon and L. P. Lee, "Focal length control by microfabricated planar electrodes-based liquid lens (μPELL)," Transducers Eurosensors, Germany, 10-14 June, (2001)

S. Kwon and L. P. Lee, "Focal length control by microfabricated planar electrodes-based liquid lens (μPELL)," Transducers Eurosensors, Germany, 10-14 June, (2001)

Supplementary Material (2)

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» Media 2: MOV (2179 KB)     

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Figures (7)

Fig. 1.
Fig. 1.

(a) Schematic view of deformation mechanism of a deformable liquid crystal droplet lens (not to scale) (b) Design of concentric ITO electrode of 50μm in width and 50μm in spacing.

Fig. 2.
Fig. 2.

The lens images were observed under crossed polarizers. (a) nematic phase at 20°C; (b) isotropic phase at 30°C.

Fig. 3.
Fig. 3.

The transmission spectrum of liquid crystal of the thickness of 700μm.

Fig. 4
Fig. 4

(a) Tuning focal length of a liquid crystal droplet lens changes under different applied voltages. The temperature was 30°C. (b) (2.12MB) Movie of the focal length tuning of the liquid crystal droplet lens. (9.16 MB version)

Fig. 5.
Fig. 5.

Experimental profiles of a liquid crystal droplet lens with respect to increasing applied voltage at 1 kHz.

Fig. 6.
Fig. 6.

Experimental results of effective focal length and contact angle versus applied voltages. Both the width and spacing of electrodes were 50μm.

Fig. 7.
Fig. 7.

Δf/f0 and Δθ decrease with wider electrode spacing. The electrode width is 50μm. (Δf/f0) is the tuning ratio of focal length, f0 is the focal length of liquid crystal droplet lens at 0V. Δθ is the maximum of change in contact angle. Both Δf/f0 and Δθ were measured in the range of 0-200V at 1 kHz.

Tables (1)

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Table 1. Performance comparison of liquid crystal droplet lens and water-based liquid lens

Equations (1)

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f = 1 2 ε 0 ( ε / / 1 ) E 2

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