PDMS-based, magnetically actuated variable optical attenuators obtained by soft lithography and inkjet printing technologies

• Magnetic elastomer is implanted by a combination of soft lithography and inkjet printing techniques.
• Bilayer magnetically actuated variable optical attenuators are fabricated by soft lithography technique.
• With inkjet printing technology, a selective dispensing of ferrofluidic microdrops with a controllable volume is achieved.
• Ferrofluidic droplets are encapsulated inside the elastomeric structure using a combination of soft lithography and inkjet printing techniques.
• Increase the deflection and the relative optical losses with the applied magnetic field.

This paper reports and compares the implementation of magnetic variable optical attenuators (M-VOA) by two fabrication strategies. In the first case, a two-layer structure containing a non-doped polydimethylsiloxane (PDMS) layer on a magnetic PDMS (M-PDMS) layer is fabricated by soft lithography (SLT). M-PDMS is obtained by doping PDMS with different ferrofluid (FF) volumes. The second technology consists of selectively dispense FF microdroplets using the inkjet printing technique (IJP) on a non-doped, non-cured PDMS structure, previously defined by SLT. In this second case, FF volumes are encapsulated inside the polymer matrix. The optical and mechanical properties of structures fabricated using both strategies and containing similar ferrofluid amounts are compared.