Self-cleaning surfaces using anisotropic ratchet conveyors

This paper describes an active self-cleaning surface where an optically flat and transparent anisotropic ratchet conveyor (ARC) guides a water droplet under orthogonal vibrations. Droplet transport speed is 32.9 mm/s at frequency 52 Hz and acceleration 4.8 g (g = 9.8 m/s
²
). ARC surfaces can work with a wide frequency bandwidth at 20~500 Hz as well as with surface inclination angles up to 15°. Optical transmission measurements show that the loss due to ARC coating is within 1% at visible wavelengths. The self-cleaning surface has potential applications on photovoltaic module cover glass to remove dust accumulation and improve efficiency.