Characterization of ultraviolet light cured polydimethylsiloxane films for low-voltage, dielectric elastomer actuators

Tino Töpper; Fabian Wohlfender; Florian Weiss; Bekim Osmani; Bert Müller

doi:10.1117/12.2218608

15 April 2016 Characterization of ultraviolet light cured polydimethylsiloxane films for low-voltage, dielectric elastomer actuators

Tino Töpper, Fabian Wohlfender, Florian Weiss, Bekim Osmani, Bert Müller

Author Affiliations +

Proceedings Volume 9798, Electroactive Polymer Actuators and Devices (EAPAD) 2016; 979821 (2016) https://doi.org/10.1117/12.2218608
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2016, Las Vegas, Nevada, United States

Abstract

The reduction the operation voltage has been the key challenge to realize of dielectric elastomer actuators (DEA) for many years - especially for the application fields of robotics, lens systems, haptics and future medical implants. Contrary to the approach of manipulating the dielectric properties of the electrically activated polymer (EAP), we intend to realize low-voltage operation by reducing the polymer thickness to the range of a few hundred nanometers. A study recently published presents molecular beam deposition to reliably grow nanometer-thick polydimethylsiloxane (PDMS) films. The curing of PDMS is realized using ultraviolet (UV) radiation with wavelengths from 180 to 400 nm radicalizing the functional side and end groups. The understanding of the mechanical properties of sub-micrometer-thin PDMS films is crucial to optimize DEAs actuation efficiency. The elastic modulus of UV-cured spin-coated films is measured by nano-indentation using an atomic force microscope (AFM) according to the Hertzian contact mechanics model. These investigations show a reduced elastic modulus with increased indentation depth. A model with a skin-like SiO₂ surface with corresponding elastic modulus of (2.29 ± 0.31) MPa and a bulk modulus of cross-linked PDMS with corresponding elastic modulus of (87 ± 7) kPa is proposed. The surface morphology is observed with AFM and 3D laser microscopy. Wrinkled surface microstructures on UV-cured PDMS films occur for film thicknesses above (510 ± 30) nm with an UV-irradiation density of 7.2 10^-4 J cm^-2 nm^-1 at a wavelength of 190 nm.

Conference Presentation

Citation Download Citation

Tino Töpper, Fabian Wohlfender, Florian Weiss, Bekim Osmani, and Bert Müller "Characterization of ultraviolet light cured polydimethylsiloxane films for low-voltage, dielectric elastomer actuators", Proc. SPIE 9798, Electroactive Polymer Actuators and Devices (EAPAD) 2016, 979821 (15 April 2016); https://doi.org/10.1117/12.2218608

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