Ultrasound-driven droplet transport: A novel dust removal strategy for optical surfaces

This study proposes a novel dust removal strategy for optical surfaces based on ultrasound-driven droplets, revealing for the first time the motion characteristics and cleaning mechanisms of droplets on dust-covered surfaces under ultrasonic excitation. A piezoelectric ceramic-glass substrate coupled vibration system was developed, and experimental investigations were conducted on dust collection and removal via ultrasound-driven droplets. The results indicate that acoustic streaming drag force dominates dust motion within droplets under ultrasonic actuation, achieving a movement speed of 20.8 mm·s⁻¹ for dust with a coverage density of 10 g·m⁻². The visible light transmittance of the cleaned area improved from 16 % to 93 %. By analyzing the impedance characteristics of the piezoelectric ceramics and substrate vibrations, 650 kHz was identified as the optimal driving frequency. The droplet movement speed increases with voltage, exhibiting a driving threshold of 40 V and a splashing threshold of 75 V, while peaking at a droplet volume of 140–160 μL. In the case of cleaning photovoltaic panel surfaces, the energy consumption of this method accounts for only 0.46 % of the additional power generated post-cleaning daily, with water usage reduced by over 90 % compared to conventional spray cleaning. This study offers an innovative solution for water-efficient and high-performance glass surface cleaning in arid regions.