Superamphiphobic Bionic Proboscis for Contamination-Free Manipulation of Nano and Core-Shell Droplets

Manipulation of nanoliter droplets is a key step for many emerging technologies including ultracompact microfluidics devices, 3D and flexible electronic printing. Despite progress, contamination-free generation and release of nanoliter droplets by compact low-cost devices remains elusive. In the present study, inspired by butterflies' minute manipulation of fluids, the authors have engineered a superamphiphobic bionic proboscis (SAP) layout that surpasses synthetic and natural designs. The authors demonstrate the scalable fabrication of SAPs with tunable inner diameters down to 50 mu m by the rapid gas-phase nanotexturing of the outer and inner surfaces of readily available hypodermic needles. Optimized SAPs achieve contaminationfree manipulation of water and oil droplets down to a liquid surface tension of 26.56 mN m(-1) and a volume of 10 nL. The unique potential of this layout is showcased by the rapid and carefully controlled in-air synthesis of core-shell droplets with well-controlled compositions. These findings provide a new low-cost tool for high-precision manipulation of nanoliter droplets, offering a powerful alternative to established thermal-and electrodynamic-based devices.