Exploring lead-free materials for screen-printed piezoelectric wearable devices
Zois Michail Tsikriteas, James Roscow, Chris Bowen, Hamideh Khanbareh
Abstract
The rapid advancements in wearable technology demand innovative materials that are flexible, lightweight, and environmentally sustainable. Here, we report the formulation, characterization, and application of screen-printed piezoelectric inks consisting of barium titanate (BT), barium calcium zirconate titanate (BCZT), and potassium sodium niobate (KNN) for flexible piezoelectric sensors. X-ray diffraction and scanning electron microscopy reveal high crystallinity and distinct morphologies. Rheological experiments show excellent printability; however, the BCZT-based ink reveals shear thickening behavior and a lower recovery rate of 63.5% during printing. Thermal gravimetric and Fourier transform infrared spectral analyses provide insights into the inks' thermal and chemical stability. The screen-printed composites exhibit excellent adhesion to the substrates and consistent dielectric properties across a wide frequency range. A detailed investigation of the piezoelectric charge coefficient d 33 under varying poling conditions is carried out using corona discharge poling. The study provides a comprehensive understanding of the role of ceramic fillers in influencing the rheological, thermal, and piezoelectric properties of screen-printed piezoelectric inks, guiding the development of customizable flexible sensors.