Evaluation of drag force of a thrip wing by using a microcantilever

Abstract

Tiny flight-capable insects such as thrips utilize a drag-based mechanism to generate a net vertical force to support their weight, owing to the low associated Reynolds number. Evaluating the drag generated by such small wings is of considerable significance to understand the flight of tiny insects. In this study, a self-sensing microcantilever was used to measure the drag force generated by an actual wing of a thrip. The wing of a thrip was attached to the tip of the microcantilever, and the microcantilever along with the wing was affixed perpendicular to a constant airflow at the middle of a bench-top wind tunnel. The drag generated by the wing under airflow velocities in the range of 0–4.8 m/s was obtained. In addition, the drag generated by the wing was verified by performing a three-dimensional computational fluid dynamics analysis. At a biological average wing tip velocity of 0.7 m/s, the difference between the measured drag force (290 nN) and calculated drag force (300 nN) was merely 3.3%. This new approach of evaluating the drag force generated by tiny insects could contribute to enhancing the understanding of microscale flight.