Fabrication and Electromechanical Characterization of Piezoelectric Patches for OLED-Based Haptic Interfaces

Digital interfaces have become ubiquitous in recent years, and many applications requiring tactile interaction have the potential to be enhanced by haptic feedback. Blind and partially-sighted people in particular could benefit greatly from a digital interface with haptic feedback, enabling them to be better included in the modern digital space. In this paper, we present a flexible patch containing a matrix of piezoelectric actuators and the connectivity required for its instrumentation. When integrated into an OLED screen, this patch creates a vibrotactile sensation that is easily perceptible on the screen surface. The article presents a detailed manufacturing process for the patch, a lumped elements model used to confirm the reliability of the manufacturing process, and a finite element model that provides a realistic representation of the patch's behavior integrated with the OLED screen. Subsequent to the fabrication of a first prototype, an electromechanical characterization step was conducted, which highlighted the quality of the mechanical coupling between the patch and the screen. A measurement campaign employing a Doppler laser vibrometer then enabled the refinement of the finite element model, thereby confirming the piezoelectric patch's capacity to generate a vibration amplitude of over 125 nm/V at 300 Hz over a substantial area of the OLED screen. This displacement amplitude is compatible with a haptic effect using some tens of Volts.