3D printing of soft magnetoactive superhydrophobic elastomers for droplet manipulation

Soft responsive surfaces have generated significant interest due to their dynamic control over wetting behaviors through geometrical reorganization in response to external stimuli. Here, magnetoactive elastomeric surfaces are 3D printed using the direct ink writing technology. By designing a "high-wall" structure, superhydrophobic ability is achieved, with water contact angle of 152 degrees and a sliding angle of 9 degrees. The mechanical softness of the elastomer allows for reversible geometrical changes under magnetic field. This deformation can be precisely controlled by adjusting the strength and position of the magnet, causing the water droplet to move towards the desired location with a speed of 3.33 mm/s. This study introduces a new strategy for achieving lossless transportation of mu L-scale nonmagnetic droplets, which holds potential for applications in microfluidics and soft robotics.