Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 1: Application of Thin Films

DS 1.8: Talk

Monday, March 31, 2014, 11:30–11:45, CHE 91

Design, fabrication and performance of polymer actuators for on-chip variable focal length microlenses — •Christian Schirrmann, Boscij Pawlik, Kirstin Bornhorst, and Florenta Costache — Fraunhofer Institute for Photonic Microsystems IPMS, Dresden, Germany

We employed the finite element method (FEM) to simulate the electromecanical behavior of monolayer and multilayer bending actuators based on PVDF-TrFE-CFE (61.7%/29.8%/8.5%) terpolymer of high electrostrictive strain. The actuator geometry (i.e. radial shape), the actuator stack structure, the polymer layer thickness, as well as the electrode material were adjusted in order to improve the deflection characteristics of the actuator. For the actuator fabrication, a layer-by-layer process flow was developed, which included polymer and metallic electrode layers deposition, structuring and direct bonding. The analysis of the actuator performance by means of interferometric methods indicated that very large deflections could be obtained. Furthermore, the optimized terpolymer bending actuator was employed in the design of a microlens with electrically adjustable focal length. This microlens consisted of two microfluidic compartments sealed by an elastic lens membrane. Here, the integrated actuator played the role of a pump. The variable micro-lens chip geometry was optimized using 3D-FEM simulations and fabricated using planar microtechnology. For a microlens with 3 mm aperture diameter, we could achieve a tuning range in the refractive power between 0 and more than 20 dpt for fairly low operation voltages.