Novel Microwave Sensor for Quality Assurance of Indoor Residual Spraying

Vector-borne diseases, such as visceral leishmaniasis or malaria, are a significant global burden, particularly in low- and middle-income countries in regions with high parasite prevalence. Indoor residual spraying is one of the most effective control tools, if performed effectively. Current World Health Organization (WHO)-recommended quality assurance methods are costly, require skilled staff, and are time consuming. This letter presents the development of a novel microwave sensor for quality assurance of indoor residual spraying. The developed prototype was tested in controlled laboratory settings, and during two field studies conducted during dry and wet seasons in Bihar, India. The results demonstrated the potential of a rapid, nondestructive microwave sensor system for detecting alpha-cypermethrin residues, offering an improvement over current quality assurance methods. The sensor achieved high cross-validation accuracy in controlled laboratory settings (mean 100%, standard deviation 0%), while the performance in the field studies was reduced (mean 84.63%, standard deviation 1.98%) due to real-world complexities. Future development steps will include the miniaturization of the sensor system and the implementation of advanced signal processing techniques to reduce noise and compensate for environmental effects.