Stabilizing The Cone-Jet Mode in Electrospray Through Ground Current Monitoring

Electrospray deposition (ESD) is a spraying process which utilizes a high voltage emitter to create monodisperse, micron scale droplets. These droplets carry a charge and are highly influenced by the force of the electric field which directs them towards a grounded target. As the droplets contact the grounded surface they deposit their charge, generating a nanoamp current in the process. ESD can take place in one of a few distinct spray modes: dripping, micro-dripping, cone-jet, and multijet. Although there are several factors that determine spray mode, we chose to utilize applied voltage as a means of controlling spray mode. Our application leverages ESD, specifically the cone-jet spray mode, as a means of efficient nutrient delivery to plants. As a part of this project, we have automated the spraying process by monitoring the nanoamp ground current. Specifically, we developed a Python program that analyzes the current signal in discrete time intervals and calculates key statistics such as mean, median, and standard deviation as well as the Fast Fourier Transform of the signal. Based on this information, the program autonomously determines which applied voltage will result in a stable cone-jet spray mode.