Acoustophoretic system for seed separation on conveyor belts

Seed sorting on conveyor belts is a vital part of the modern agriculture industry, allowing for substandard seeds to be identified and ejected before germination. Conventional sorting systems typically rely on air-jet ejection, which can be expensive and limited in both accuracy and flexibility. Ultrasonic phased array transducers offer an alternative solution for seed separation on conveyor belts that addresses many of these issues. These arrays can generate focused beams of sound energy that affect small objects through acoustic radiation forces and offer precise, programmable control. Here we show that by combining phased arrays with a camera detector, seeds can be selectively identified and acoustically ejected based on quality metrics such as size and color. Unlike binary sorting methods, our system allows for variable ejection distances, enabling more nuanced categorization. We validate our approach through extensive experiments in both static and dynamic conditions, demonstrating effective separation not only of sub-standard seeds but also of unwanted debris. This acoustophoretic system is low-cost, adaptable, and capable of advanced functionalities such as mid-air hovering for seed alignment, full levitation for quality inspection or coating, and ejection in a free-fall environment. Our findings suggest a promising direction for next-generation agricultural automation and precision sorting systems.