Rapid Sampling of Tomato Juice Using a 3D-Printed Microneedle Assisted by an Unmanned Aerial Vehicle

Extracting tomato juice for maturity assessment is critical for ensuring a timely harvest. Nevertheless, the limitations of existing sampling tools and heavy reliance on manual operation may result in tomatoes being harvested outside their optimal window, resulting in economic losses. Therefore, there is an urgent need for a better method for tomato juice sampling and maturity monitoring. In this work, an unmanned aerial vehicle (UAV)-mediated directional sampling system (uDSS) was developed for tomato identification in the field and the collection of tomato juice. The system integrates a UAV with a real-time ultra-wideband (UWB) positioning system. The system autonomously performs the flight and juice-sampling sequence; juice recovery and Brix measurement are carried out after the flight. With regard to the sampling procedure, a 3D-printed microneedle (MN) with porous synthetic paper for capillary liquid absorption was employed to penetrate the tomato and extract juice. Lastly, the sugar content of tomatoes was measured in order to verify the feasibility of uDSS. This unmanned system is expected to promote the development of UAV-based solutions in precision agriculture and intelligent food industry.