PVDF/PMMA blend pyroelectric thin films

This paper will present a complete manufacturing process for obtaining pyroelectric thin film sensors composed of a blend of PVDF and PMMA polymers. These sensors comprise a stack of metallic (Ti/Pt) electrodes around an active pyroelectric layer and are able to detect a temperature variation through the pyroelectric effect. Deposition is achieved with solution using a spin-coating and hot plate drying method. Addition of PMMA is a technique for promoting the crystallization of PVDF in the β phase, with one of the PVDF polymer chain conformations producing a ferroelectric behaviour. Analysis of the role of the solvent evaporation rate has been carried out with FTIR and indicates that low temperature evaporation (below 70 °C) leads to the presence of β phase in the material. Polarization curve measurement also indicates the ferroelectric behaviour of deposited layers. Finally a thermal transient response indicates a pyroelectric coefficient of 20 μC m⁻² K⁻¹ which is close to the bulk material value (27 μC m⁻² K⁻¹).