These images showed that the valves attached to each lancet – both of which sit in the poison pumping chamber – change shape as they slide back and forth during pumping. They inflate like a parachute on the downward stroke, creating a seal through a piston-like action that applies downward pressure in the chamber to force the poison out. They deflate upon impact. And when the valves meet in the middle, they change shape again to slide past each other.
“The unique geometry of the valves is key; they act as collapsible pistons and – by pumping in opposite directions – can deliver a continuous flow of poison,” said co-author Fiorella Ramirez-Esquivel from Macquarie University. “The dual piston design adds complexity but is key to allowing the Stinger to continuously deliver venom in a compact, autonomous unit.” The double movement also minimizes backflow.
These results were consistent with the authors’ preliminary flow visualization experiments. To verify the initial results, the team took micro-CT scans and used this data to create a 3D printed, full-scale prototype model to mimic the observed pumping behavior. This pumping movement was also filmed and analyzed frame by frame. The artificial pump model showed the same pumping kinematics as the biological spikes.
Future research could focus on a closer look at the material properties of the valves, as the team’s artificial polymer valve shows that extremely high elasticity is key to replicating the necessary valve deformations, along with low friction between the valves. Given the small size of the toxic pump elements, it would also make sense to investigate whether capillary action plays a role. Capillary action could help draw the venom into the venom canal, or alternatively the venom may need to counteract capillary action, which serves to draw fluid from the tissue.
Previous research has used the structure of the bee stinger as inspiration for the development of microneedles, tissue delivery devices and drilling devices. The authors believe their own work will eventually find similar medical and microfluidic applications, such as for artificial pumps.
DOI: PNAS, 2026. 10.1073/pnas.2603916123 (About DOIs).
