Abstract

Dielectric polymer actuators (often referred to as “artificial muscles”) require electrodes that conduct at strains of over 40% and that are not stiffer than the elastomer. On the macro-scale, such attributes are readily achieved with carbon powder electrodes. When shrinking polymer actuators to the micron scale however, a different solution is needed. We present a novel technique for making highly compliant electrodes on elastomers (PDMS) using low-energy metal ion-implantation. This technique forms nanometer scale metallic clusters up to 50 nm below the PDMS surface, creating an electrode that can sustain up to 175% strain while remaining conductive, yet having only a minimal impact on the elastomer’s mechanical properties. These electrodes are readily patterned on the μm scale by masking with patterned photoresist or laser-cut steel masks. They are stable in time (no resistivity or stiffness change over 2 years) and show only minor changes in electrical characteristics after 105 cycles of 30% strain. Using these ion-implanted compliant electrodes, we have microfabricated circular diaphragm actuator of diameter 1.5 to 3 mm, with voltage-controlled static out-of plane deflections of over 25% of their diameter, and response times faster than 1 ms. Lifetime tests have shown no degradation after more than 4 million cycles at 1.5 kV. Applications in tunable optics and cell manipulation will be presented. Finally a brief overview of our lab’s other activities will be given, in the field of MEMS for space (micro-propulsion and inertial sensing).