Butterfly proboscis inspires pump-free air sampler costing cents per unit

Scientists at the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences have created a pump-free airborne sampler inspired by the feeding mechanism of butterflies. The device, called Film-Rupture Actuated Capillary Enrichment (FACE), was described in a recent paper in Proceedings of the National Academy of Sciences.

X-ray imaging revealed that a coiled butterfly proboscis traps a thin liquid film at its center. As the film thins, it reaches a critical point and ruptures, releasing stored surface energy that drives the remaining liquid rapidly into the feeding tube without muscle action. The researchers replicated this mechanism in a coin-sized, 3D-printed device containing a ring-shaped liquid film connected to capillary channels.

During sampling, the exposed liquid film captures airborne targets such as pollutant gases, pesticide particles, and virus-containing droplets. When a test strip contacts the device, the film ruptures and the stored surface energy propels the collected liquid and its contents through the capillaries directly into a detection zone. The process requires no pump, battery, or external power source.

In field tests, the sampler remained effective in strong airflow, making it suitable for mounting on agricultural drones to monitor pesticide residues above crops. For infectious disease monitoring, the lightweight device can be positioned near a person's face to capture exhaled bioaerosols before they dilute in the surrounding air.

Experiments targeting the SARS-CoV-2 nucleocapsid protein showed the FACE platform achieved detection sensitivity 100 times higher than conventional pump-based aerosol samplers. Collection and recovery efficiencies approached 100%, with an overall dilution ratio of only 1.14, because the system integrates collection, recovery, enrichment, and detection in a single workflow without tubing losses.

Each disposable unit costs approximately $0.12 to produce. Because the technology operates without electricity or specialized training, the researchers suggest it could be valuable in remote and resource-limited regions where conventional air-sampling infrastructure is unavailable.