Automatic wiping effect on passive dew collection

• Automatic wiping increased dew yield by up to 70 % on sandblasted surfaces. • Multiple timed wiping reshaped droplet patterns and collection. • Repeated wiping smoothed surfaces micro-rough textures, impacting long-term efficiency. Dew harvesting using Passive Dew Collectors (PDCs) offers a sustainable and economically viable solution for atmospheric water capture, particularly in water-scarce regions. However, droplet collections are often hindered by pinned droplets to the surface reducing the overall collection efficiency. This study investigates the impact of automatic wiping on dew collection performance, droplet formation dynamics, and surface morphology. Field experiments conducted in Viikki, Finland, over 54 dew-active nights compared standard and sandblasted PDCs with and without automated wiping mechanisms. The panels collected dew amounts ranged from 0.002 mm to 0.28 mm/night. The sandblasted wiped panel showed the highest overall yield of 6.67 mm, collecting 70.1 % more water than its unwiped counterpart. Compared to previous studies reporting 27–51 % yield improvements from manual wiping, the enhanced performance was possibly due to implementing the multiple timed wiping intervals (at 2 hrs intervals between 12 – 6 a.m.) during peak condensation hours. Image analysis revealed that wiping disrupts uniform droplet nucleation, leading to localized condensation and persistent water channel formation. Surface analysis further indicated that repeated wiping smooths micro-rough textures, potentially reducing long-term nucleation efficiency and reduction in collected dew amount. Overall, the implementation of automatic wiping enhanced dew collection performance, and future optimization of wiping intervals and surface durability can further improve the viability of PDCs in arid and semi-arid environments.