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Dynamic piezoelectric response of cellular micro-structured PDMS ferro-electret material under the impact of polymeric reticulation

Auteur(s) : A. Kachroudi, S. Basrour, L. Rufer, F. Jomni

Doc. Source: First International Symposium on Dielectric Materials and Applications (ISyDMA'16)

Pages : 152

In this paper, we propose a novel low-cost implementation process of the charged cellular micro-structured polydimethylsiloxane (PDMS) material [1] referred as piezo-electret or ferro-electret material. The cellular micro-structured PDMS was prepared using the two elements of the Sylgard 184 elastomer kit from Dow Corning: the pre-polymer and the curing agent. Thanks to the effect compromise between their lower Young’s modulus and higher piezoelectricity compared to a conventional ferroelectric polymer and ceramic piezoelectric material, this type of material is suitable for micro-sensors applications and wearable energy harvesting. The micro-structured ferro-electret PDMS material is presented as sandwich of three layers (two bulk layers of 55μm thicknesses separated by a micro-structured layer of 40μm thickness containing cylindrical micro-cavities of 50μm radius with a pitch of 150μm). This configuration was chosen after analytical simulations to optimize the piezoelectric response of the piezo-electret material. The structures were poled by a direct contact charging process under a quasi-static triangular voltage of 0.5Hz frequency and with amplitudes between 1Kv and 4Kv for 15min to ionize the air and to implant charge in the inner surfaces of the voids [2]. This breakdown criterion for this configuration is predicted by the Paschen’s law. The resulting micro-structured PDMS material has a piezoelectric behavior and can interconvert a mechanical signal into an electrical one. Different samples with different reticulation degree of the basic PDMS material were implemented to study its impact on the piezoelectric properties of the cellular material. Dielectric spectra were measured under inert gas with dielectric analyzer (Novocontrol Alpha) to investigate the piezoelectricity of different samples in the frequency range between 100Hz and 1MHz [3]. The dielectric spectra exhibit piezoelectric thickness-extension resonant peaks through which piezoelectric coefficient could be determined in order to study the effect of the polymeric reticulation on the piezoelectric properties of different samples.