Flexible PDMS micro-lens array with programmable focus gradient fabricated by dielectrophoresis force

Micro-lens arrays with programmable focus gradient were fabricated using polydimethylsiloxane (PDMS) droplets on a polyethylene (PE) membrane which isolates PDMS from concentric circular electrodes. The copper electrodes were patterned on a flexible print circuit so that gradient voltages could be applied on the droplets to generate dielectrophoresis forces of gradient magnitudes. The radii of curvature of the droplets changed from 0.9 to 1.6 mm when the applied bias voltage increased from 0 to 350 V. After curing the PDMS lenses, the PE substrate was peeled off to form a flexible PDMS micro-lens array. An 8 x 8 lens-array with focus gradient has been demonstrated. (C) 2011 Elsevier B.V. All rights reserved.