Optimizing air-assistance for an electrostatic sprayer integrated with intelligent spray control in a greenhouse environment

Authors: HERKINS, MATTHEW - The Ohio State University; Zhu, Heping; Jeon, Hongyoung; ZHAO, LINGYING - The Ohio State University

Submitted to: Smart Agricultural Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2026
Publication Date: 5/7/2026
Citation: Herkins, M., Zhu, H., Jeon, H., Zhao, L. 2026. Optimizing air-assistance for an electrostatic sprayer integrated with intelligent spray control in a greenhouse environment. Smart Agricultural Technology. 14. Article 102190. https://doi.org/10.1016/j.atech.2026.102190.
DOI: https://doi.org/10.1016/j.atech.2026.102190

Interpretive Summary: Greenhouse crops require intensive use of pesticides to ensure healthy plant growth during their entire life cycle. Precision spray technologies are needed to improve greenhouse production efficiency and prevent workers and the environment from exposure to excessive pesticide waste. In this research, an air-assisted electrostatic spraying system was first investigated in a wind tunnel by determining its optimal air velocity and charging voltage to obtain maximal spray deposition inside plants. It was further investigated in a greenhouse by integrating the system with a laser sensor-guided intelligent variable-rate spray control attached to a watering boom system. The integrated spray system increased spray deposition between 36% and 49% with significant improvement of spray deposition uniformity and reduction of overspray compared to conventional sprayers. Thus, the integration of electrostatic spray system with air assistance and intelligent control achieved precision application of pesticides on target plants and will benefit U.S. greenhouse growers to save production cost from using less pesticides and other agrochemical inputs with safer working environments.

Technical Abstract: An electrostatic spraying system integrated with air-assistance was evaluated to enhance canopy deposition in a wind tunnel and a greenhouse environment under varying air speeds and droplet charge-to-mass ratios. Experimental results in a wind tunnel revealed that under still-air conditions, an air-assistance speed of 10 m/s optimized spray performance, achieving a peak average canopy coverage of 15.4% and deposition of 1.52 µg cm-2. Under moderate wind conditions of 2.24 m/s, the optimal operational parameters shifted; maximum canopy deposition was observed at an air-assistance speed of 15 m s-1, while maximum coverage occurred at 20 m/s. Subsequent greenhouse experiments compared conventional and variable-rate ‘intelligent’ spraying systems, both electrostatically and non-electrostatically, to quantify canopy coverage, spray uniformity, and overspray potential. Electrostatic sprays relatively enhanced average coverage by 21.5% and 26.8% for conventional and intelligent systems, respectively, compared to the non-electrostatic counterparts. When combined with air-assistance, electrostatic charging relatively increased coverage by 49.1% for the conventional system and 35.5% for the intelligent variable-rate system relative to the conventional non-electrostatic system. Additionally, the intelligent system significantly improved the spray uniformity index and minimized overspray potential. These findings demonstrate that integrating intelligent control with the air-assisted electrostatic spraying system could provide optimal applications with maximized canopy penetration and minimized off-target waste in a greenhouse environment.