Electrical and mechanical characterization of medical grade silicones as dielectric layers in aerosol jet printed dielectric elastomers

Abstract

The name artificial muscles has given dielectric elastomer actuators much attention in the field of medical technology. In healthcare applications, these compliant materials are particularly suitable for soft and lightweight actuators and in addition, they show many advantageous properties such as great extensibility for on-body sensors. However, the lack of industrial scaled production capabilities is still a limiting factor in the transfer of these promising materials into a broad application. To address this issue, we have modified an aerosol jet printer for automated stacking of electrodes and dielectric layers in one process device, which is described in earlier publications. As the performance is mainly dependent on the electrical and mechanical characteristics of the dielectric, a broad material variety is required to face different tasks in healthcare technology. Therefore, different medical grade silicones are investigated in this paper regarding the suitability for aerosol jet printing. In a first step, the printing parameters are derived from rheological testing of the uncured components that are used pure and in mixture with silicone oils to vary the specific Young’s module. Through heat application and dilution, the range for printable materials increases to silicones with initial viscosities up to 8200 mPas. Subsequently aerosol jet printing is used to manufacture stacked silicone dielectrics that are then investigated regarding their mechanical and electrical characteristics for dielectric elastomers. Finally, the collected parameters are compared and an overview of the feasible property combinations is given which can be used as a material guideline for different applications.