Abstract

An elastomer-based tunable liquid-filled microlens array integrated on top of a microfluidic network is fabricated using soft lithographic techniques. The simultaneous control of the focal length of all the microlenses composing the elastomeric array is accomplished by pneumatically regulating the pressure of the microfluidic network. A focal length tuning range of hundreds of microns to several millimeters is achieved. Such an array can be used potentially in dynamic imaging systems and adaptive optics.

© 2003 Optical Society of America

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References

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  1. M. H. Wu, G. M. Whitesides, �??Fabrication of Diffractive and Micro-optical Elements Using Microlens Projection Lithography,�?? Adv. Mater. 14, 1502 (2002).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  10. J. Cooper MC Donald, George M. Whitesides, �??Poly(dimethylsiloxane) as a Material for Fabricating Microfluidic Devices,�?? Acc. Chem. Res. 35 (7), 491-499 (2002).
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    [CrossRef]

Acc. Chem. Res.

J. Cooper MC Donald, George M. Whitesides, �??Poly(dimethylsiloxane) as a Material for Fabricating Microfluidic Devices,�?? Acc. Chem. Res. 35 (7), 491-499 (2002).
[CrossRef]

Adv. Mater.

M. H. Wu, G. M. Whitesides, �??Fabrication of Diffractive and Micro-optical Elements Using Microlens Projection Lithography,�?? Adv. Mater. 14, 1502 (2002).
[CrossRef]

Appl. Opt.

Appl. Phys. Lett.

D. Zhang, V.Lien, Y. Berdichevsky, J. Choi, Y.H. Lo, �??Fluidic adaptive lens with high focal length tunability,�?? Appl. Phys. Lett. 82 (19), 3171-3172 (2003).
[CrossRef]

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

J. Microelectromech. S.

J. Byung-Ho, L.M. Van Lerberghe, K.M. Motsegood, D.J. Beebe, �??Three-Dimensional Micro-Channel Fabrication in Polydimethylsiloxane (PDMS) Elastomer,�?? J. Microelectromech. S. 9 (1), 76-81 (2000).
[CrossRef]

J.C. Roulet, R. Volkel, HP Herzig, E Verpoorte, NF de Rooij, R Dandliker, �??Fabrication of multilayer systems combining microfluidic and microoptical elements for fluorescence detection,�?? J. Microelectromech. S. 10 (4), 482-491 (2001).
[CrossRef]

J. Micromech. Microeng.

C. Luo, J. Garra, T.W. Schneider, R. White, J. Currie, M. Paranjape, �??Determining local residual stress of polydimethylsiloxane using ink dots, and stiffening polydimethylsiloxane using SU-8 particles,�?? J. Micromech. Microeng. 12 (5), 677-681 (2002).
[CrossRef]

LEOS 2001

O. Matoba, E. Tajahuerce, B. Javidi, �??Three-dimensional object recognition based on multiple perspectives imaging with microlens arrays,�?? LEOS 2001. 14th Annual Meeting of the IEEE Lasers and Electro-Optics Society. Part vol.2, pp.495-6, 2001, Piscataway, NJ, USA.

Opt. Commun.

H. Hamam, �??A two-way optical interconnection network using a single mode fiber array,�?? Opt. Commun. 150, 270 (1998).
[CrossRef]

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

Transducers ???01

S. Kwon, and L. P. Lee, �??Focal length control by microfabricated planar electrodes-based liquid lens (µPELL),�?? 11th International conference on solid-state sensors and actuators: Transducers�??01, Munich, Germany, June 10-14, 2001.

Other

ABCR 1994/1995. Research Chemical and Metals.

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Figures (13)

Fig. 1.
Fig. 1.

Optical micrograph of the microlens array. Upon pressurizing the elastomeric liquid filled chamber, the membrane deforms forming a plano-convex lens array.

Fig. 2.
Fig. 2.

The fabrication process for integrating microfluidics on bottom of the microlens array (the dotted lines represent a microchannel that connects the two chambers but is not on the same plane as the above cross-sectional view).

Fig. 3.
Fig. 3.

Spectral transmission range of PDMS elastomer (the spectrum was obtained from 1 mm thick PDMS sample using an Ocean Optics SD2000 spectrometer).

Fig. 4.
Fig. 4.

Optical interferometric image of a single PDMS microlens at 20 KPa.

Fig. 5.
Fig. 5.

Maximum membrane deflection versus pressure. The maximum deflection is normalized to the initial zero-pressure deflection.

Fig. 6.
Fig. 6.

Cross section view of the PDMS membrane pressurized at 20 KPa (the scale represents vertical displacement in microns). The finite element simulation reveals two radii of curvature.

Fig. 7.
Fig. 7.

Outer and inner radius of curvature versus applied pressure.

Fig. 8.
Fig. 8.

Measured profile of the outer lens surface and curve fitting using sixth order polynomials. Table 1 below summarizes the polynomial coefficients as well as the simulated spherical aberrations.

Fig. fig08.1
Fig. fig08.1

Table 1. Polynomial Coefficients

Fig. 9.
Fig. 9.

The experimental setup for measuring the focal length of the variable-focus microlens.

Fig. 10.
Fig. 10.

Focal length versus pressure for an oil and UV curable polymer-filled microlens.

Fig. 11.
Fig. 11.

Percentage focal length change versus pressure for an oil-filled and UV curable polymer-filled (Norland 63) microlens.

Fig. 12.
Fig. 12.

Variable focusing of the oil-filled microlens array by changing the pressure. A sharp focused spot is obtained when the focal plane comes in focus.

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