Microphone based on Polyvinylidene Fluoride (PVDF) micro-pillars and patterned electrodes

Abstract

Piezoelectric materials have the ability to transfer energy between the electric and mechanical domains. Polyvinylidene fluoride (PVDF) exhibits higher piezoelectricity than other polymer materials such as nylon and polyvinyl chloride. PVDF is a superior material for sensors because its stress constant, the ability to convert stress into electrical energy, is more than 20 times higher than that of lead zirconate titanate. Nonetheless, there is significant interest in improving the effective stress constant of PVDF devices beyond the intrinsic sensitivity of the material. Significant research has focused on improvements in material properties, such as increasing β phase ratio or artificially introducing defects, and processing, such as optimizing stretch ratio and poling temperature or applying a high electric field. This research is focused on

Versatile methods for the fabrication of polyvinylidene fluoride microstructures

“…For one, there are expected differences in mechanical compliance between patterned microstructures and flat sheets. A poled PVDF micropillar is not constrained by any surrounding material along and around its sidewalls; therefore it is anticipated to exhibit more deformation in response to an electric field, in comparison to a solid PVDF sheet (Dubach et al 2009;Xu et al 2009). In addition, previous studies have also shown that the pressure and temperature-based imprinting process can lead to a improved orientation of the crystalline domains in PVDF and PVDF-TrFE films, which under certain conditions, such as electric field driven polarization, could result in improved piezoresponse (reflected in increased piezoelectric coefficients), compared to flat PVDF films (Hu et al 2005;Kang et al 2007;Liu et al 2010).…”

“…It is envisioned however that microstructured piezoelectric materials could provide improved sensitivity and functionalities to MEMS devices (Li and Bonnell 2008). Previous modeling studies suggest, for example, that micropatterned PVDF films could provide enhanced acoustic sensitivity compared to flat PVDF films (Xu et al 2009). Moreover, in regards to BioMEMS technologies, component miniaturization is important for achieving more direct interactions with biological entities at the cellular and subcellular levels.…”

Non-invasive technologies of fetal heart rate diagnosis

“…The Polyvinylidene Fluoride polymer (PVDF), discovered by Kawai is frequently using for sensor development in biomedical applications [14]. This material is having a homogenous and solid structure with approximately 50% − 65% crystallinit [15], [16].…”

Design and microfabrication of a PVDF acoustic sensor

“…Being able to increase the pillar height to diameter ratio to 4 or higher would enable the use of any amplifier input resistance and pillar heights of 15 μm or higher. Further details on the optimization procedure have been presented by Xu et al 21,22 …”