Environmentally Friendly Printable Piezoelectric Inks and Their Application in the Development of All-Printed Touch Screens

Abstract

Piezoelectric inks have been developed based on poly(vinylidene fluoride-co-trifluoroethylene), PVDF-TrFE, dissolved in the environmentally friendly solvent N,N 0 -dimethylpropyleneurea (DMPU). The inks were prepared for different printing techniques, including doctorblading, spray-printing, and screen-printing, representing therefore a relevant step for the additive manufacturing of sensors, actuators, and touch screens, among others. The rheological properties of the inks demonstrate that DMPU is a good solvent for this polymer and allows one to obtain dense piezoelectric films with the different printing techniques, showing also similar physicochemical and electrical properties. The highest piezoelectric coefficient |d 33 | = 19 pC/N is obtained for films processed by screen-printing, the piezoelectric coefficient being stable over more than 6 weeks. The corresponding PVDF-TrFE films were applied in the development of a touch screen by additive manufacturing, with two screen-printed silver electrodes in the form of an array of touch buttons. The all-printed piezoelectric touch screen allows easy fabrication and, therefore, improved integration into a variety of substrates, including flexible ones.

Flexible ferroelectric wearable devices for medical applications

“…To achieve such a flexible electrode material with high stretchability, low processing temperature and low resistance, a variety of conductive materials and processing technologies have been studied. Different conventional inorganic materials such as platinum (Pt) ( Dagdeviren et al., 2014 ), gold (Au) ( Gonçalves et al., 2019 ), aluminum (Al) ( Zhao et al., 2020 ), indium tin oxide ( Luo et al., 2017 ), silver (Ag) ( Yoon et al., 2020 ) and copper (Cu) ( Rajala et al., 2017 ) in a variety of forms such as films, nanoparticles, nanowires or flakes, as well as some organic materials, such as CNTs and graphene, are generally considered as the most attractive options for developing conductive, flexible electrodes and interconnection elements. Inorganic materials are usually rigid which limits their use in wearable flexible systems.…”

“…Screen printed wearable piezoelectric devices have been developed for monitoring physiological signals ( Fares et al., 2020 ; Gonçalves et al., 2019 ; Laurila et al., 2019 ; Sato et al., 2019 ). Sekine et al.…”

Bioinspired Self‐Healing Human–Machine Interactive Touch Pad with Pressure‐Sensitive Adhesiveness on Targeted Substrates

“…However, polymer materials are incompatible with standard photolithography microfabrication technology, making it highly challenging to produce high-density sensor arrays. [1] The reported sensor array based polymer touch pads show resolutions ranging from 1 array point per 10 cm 2 [40] to 1 array point per 1 cm 2 area. [41,42] In contrast, the finger position on our hydrogel touch pad is calculated from voltages on four external resistances.…”

Electroactive poly(vinylidene fluoride)-based materials: recent progress, challenges, and opportunities

“…Although PVDF-based materials had a research climax in the last 3 years (with more than 5000 papers each year) and have been commercialized for a long time, there is still a lot of room for innovation with these materials [27]. As an example, recently a screen printable formulation with environmental friendlier solvent has been presented and the applicability in an all printed touch screen has been demonstrated [53].…”