Fully-Printed Piezoelectric Devices for Flexible Electronics Applications

Recent advances in materials and manufacturing processes pave the way for the establishment of piezoelectric materials via printing techniques as flexible sensors, actuators, and generators. Such flexible devices are key building blocks for future advanced robotic skin and conformable medical devices. Herein special focus is given to printed devices for its lightweight, flexibility, and manufacturing by high throughput techniques, offering a disruptive advantage in integration technologies and a wide range of opportunities for industrialization routes, where cost-effective applications are required. In this Progress Report, the different system parameters are discussed, pinpointing the ones that affect the production of reliable flexible printed piezoelectric devices and limit this technology to achieve higher technological maturity. Focus is made on screen and inkjet printing as fabrication techniques and the well-established piezoelectric polymer poly(vinylidene fluoride-co-trifluoroethylene). Key limiting factors found for the manufacturing of robust scalable all-printed piezoelectric devices stems mainly from the piezoelectric ink production and processing. Finally, the integration of these materials, via printing technologies, into soft, flexible, and even stretchable substrates is analyzed and insights are gathered on the manufacturing trends to achieve low-cost production of flexible piezoelectric devices embedded in electronic skin and smart wearables.