Robust Superhydrophobicity through Surface Defects from Laser Powder Bed Fusion Additive Manufacturing.

The robustness of superhydrophobic objects conflicts with both the inevitable introduction of fragile micro/nanoscale surfaces and three-dimensional (3D) complex structures. The popular metal 3D printing technology can manufacture robust metal 3D complex components, but the hydrophily and mass surface defects restrict its diverse application. Herein, we proposed a strategy that takes the inherent ridges and grooves' surface defects from laser powder bed fusion additive manufacturing (LPBF-AM), a metal 3D printing process, as storage spaces for hydrophobic silica (HS) nanoparticles to obtain superhydrophobic capacity and superior robustness. The HS nanoparticles stored in the grooves among the laser-melted tracks serve as the hydrophobic guests, while the ridges' metal network provides the mechanical strength, leading to robust superhydrophobic objects with desired 3D structures. Moreover, HS nanoparticles coated on the LPBF-AM-printed surface can inhibit corrosion behavior caused by surface defects. It was found that LPBF-AM-printed objects with HS nanoparticles retained superior hydrophobicity after 150 abrasion cycles (~12.5 KPa) or 50 cycles (~37.5 KPa). Furthermore, LPBF-AM-printed ships with superhydrophobic coating maintained great water repellency even after 10,000 cycles of seawater swashing, preventing dynamic corrosion upon surfaces. Our proposed strategy, therefore, provides a low-cost, highly efficient, and robust superhydrophobic coating, which is applicable to metal 3D architectures toward corrosion-resistant requirements.

Flexible electromagnetic capturer with a rapid ejection feature inspired by a biological ballistic tongue.

Bionics is the inspiration resource of state-of-the-art science and technology. The chameleon can capture prey at great distances with the assistance of its highly stretchable and ballistic tongue. Inspired by this biological structure, here we demonstrate the fabrication of flexible electromagnetic manipulators. The as-prepared flexible electromagnetic manipulator can reach a maximum velocity of 8.1 m s-1and acceleration of 627 m s-2at an applied voltage of 360 V. The working mechanism of this flexible electromagnetic manipulator has been studied based on Maxwell and Abaqus simulations. Diverse parameters, including the lengths of the magnetic tube (the cylindrical magnet) and the whole manipulator and the applied voltage values, have been considered to tune the ejecting performance of the manipulator. Furthermore, flexible electromagnetic manipulators can be upgraded to capture various objects by attaching a mechanical force triggered gripper to their top pads. With this design, the velocity of the gripper can be significantly improved (the maximum is 8.1 m s-1, whereas soft grippers in previous research do not have the characteristic of fast movement), thus making it possible to get objects without approaching them; in other words, we can catch objects even though they are far away from us, which provides the possibility of long-distance capture. We believe this kind of bio-inspired fabrication is a powerful strategy to design and synthesize flexible even stretchable manipulators, extending the boundaries of conventional manipulators for soft robots.