Self-cleaning drop free glass using droplet atomization/oscillation by acoustic waves for autonomous driving and IoT technology

This paper proposes a new type of self-cleaning drop free glass (DFG) using acoustic atomization and oscillation, which can be applied in autonomous driving and IoT technology. The proposed device generates acoustic waves from a ring-piezoactuator attached to the back of the glass substrate to remove contaminants on the surface. First, the acoustic atomization and behavior of droplets were observed by using a high-speed camera, and the reduction in the volume of the droplets was measured over time. Then, the atomization time of the droplets was measured according to the frequency and voltage of the ring-piezoactuator to find the application conditions of the ring-piezoactuator that atomizes the droplets most rapidly. Additionally, the behavior and atomization of viscous droplets were observed, and the atomization time of droplets with different viscosity was measured according to the frequency and voltage to compare changes in atomization depending on the viscosity of the droplets. Also, in order to check the characteristics of the ring-piezoactuator adopted in the proposed DFG, the behavior of the droplets away from the center of the ring, caused by acoustic waves, was observed. Finally, in order to verify the concept, experiments were performed to remove droplets on the surface by using acoustic atomization and oscillation technologies, respectively. The acoustic atomization removed most droplets, but left tiny satellite droplets on the substrate surface, while the acoustic oscillation completely removed all droplets on the surface. The cleaning performances were compared by using an image analysis program, and the acoustic oscillation was found to be more efficient in cleaning. The acoustic wave-based self-cleaning glass proposed in this paper can easily and effectively remove droplets with various volumes and viscosities within 1 s. Due to its simple structure and working principle, the proposed self-cleaning glass is thought to be applicable not only to cleaning of sensors for autonomous driving, but also to various industrial applications.