Magnetically-actuated variable optical attenuators using ferrofluid-doped elastomer implemented by combination of soft lithography and inkjet printing technologies

This paper reports the implementation of magnetic variable optical attenuators (M-VOA) by soft lithography (SLT) and using polydimethylsiloxane (PDMS) as constituent material. Two different fabrication protocols are used and compared. In the first case, a two-layer structure containing a clean PDMS layer on a magnetic PDMS (M-PDMS) layer is fabricated by SLT. M-PDMS is obtained by doping clean PDMS with different ferrofluid (FF) amounts. The second protocol consists of selectively dispensing droplets of FF by the inkjet printing technique (IPT) on a clean and non-cured PDMS structure previously defined by SLT. The optical and mechanical properties of structures fabricated using both protocols and containing similar ferrofluid amounts are compared.