3D Printing of Silicone Membranes as a Novel Manufacturing Process for Dielectric Elastomer Generators

Dielectric elastomer generators (DEGs) are a promising technology for harvesting renewable energy from the motion of sea waves; i.e. wave energy converters [1]. DEG devices are composites built up by combining non-conductive elastomeric polymers with layers of deformable electrodes. Silicones (i.e. polydimethylsiloxane (PDMS) and PDMS-based polymers), have been identified as the best candidates, among others (e.g. natural/synthetic rubbers and acrylic polymers), to be used as the elastomeric component in DEG devices on the base of their good potentials for (i) high conversion efficiency (achievable by targeting the relevant material properties) and (ii) industrial-scale production.

In this work, 3D printing is proposed as alternative manufacturing technology to traditional casting technique for the fabrication of silicone membranes. The novel 3D printing process is scalable and automatised, and allows for optimisation of the desired features of the membrane structure. A critical aspect is the modification (see Figure 1a) of a commercial (Modix Big 60) 3D printer to allow (i) extrusion of a viscous fluid (i.e. the non-crosslinked silicone), and (ii) the curing by UV irradiation (365 nm, 200 Watt). Quasi-static tensile tests, tension-tension fatigue tests and scanning electron microscopy (SEM) images are presented for an array of 3D- printed silicone membranes (0.5-1.5 mm in thickness, see Figure 1b). The membrane material is characterised by high stretchability (>300% elongation at break, see Figure 1c), low elastic modulus (0.8-0.9 MPa), and “near defect-free” structure, which are the required characteristics for high-performance DEGs.

Future incorporation of additives and fillers (e.g. co-polymer, carbon black/carbon nanotubes, ceramic nanoparticles) will improve the dielectric permittivity of the silicone-based membranes resulting in a composite optimised for the energy conversion application.