Fabrication of polydimethylsiloxane microlens arrays on a plastic film by proton beam writing

This paper reports the fabrication of polydimethylsiloxane (PDMS) microlens arrays (MLAs) on a 5-13 μm-thick PDMS layer on polyethylene terephthalate (PET) films using proton beam writing (PBW). The PBW is performed with a focused 1.3 μm beam with an energy of 1.0 MeV. The sensitivity of the PDMS layer on an indium tin oxide (ITO)-coated PET film is improved compared to that on a bare PET film. The arrays of the PDMS microlenses with diameters of 20 μm and a height of 4.5 μm are fabricated by changing the proton beam fluence. The ITO layer on the PET film provides substrate conductivity for PDMS and the transparency required for flexible optofluidic devices. The patterning of 35 × 35 MLAs is demonstrated in an area of 1.0 × 1.0 mm² within 16 min. The PDMS MLAs can be transferred to a Ni mold by electroplating and are then duplicated by ultraviolet imprint lithography on PET films.