Superwetting surfaces are widely used in many engineering fields for reducing energy and resistance loss. A facile and efficient method using laser etching has been used to fabricate and control superwettable drag reduction surfaces. Inspired by the self-cleaning theory of lotus leaves, we propose controllable patterned bionic superhydrophobic surfaces (BSSs) simulating the uneven micro/nanostructures of lotus leaves. The superhydrophobicity and drag reduction ratios at low velocities are highly improved using a laser ablation method on metal substrates. However, unstable air layers trapped on superhydrophobic surfaces are usually cut away by a high-velocity flow, which greatly reduces the drag reduction performance. The fabricated bionic superhydrophobic/hydrophilic surfaces (BSHSs) with alternated hydrophilic strips can build a large surface energy barrier to bind the three-phase contact line. It maintains the stable drag reduction by capturing the air bubbles attached to the hydrophilic strips at a high velocity. Three-dimensional simulation analysis and equipment to measure the weak friction of a self-assembled solid–liquid interface are used to explain the drag reduction mechanism and measure the drag reduction ratios at different flow speeds. BSSs achieve an improved drag reduction effect (maximum 52.76%) at a low velocity (maximum 1.5568 m/s). BSHSs maintain an improved and steady drag reduction effect at high speed. The drag reduction ratios can be maintained at about 30% at high speed, with a maximum value of 4.448 m/s. This research has broad application prospects in energy saving, liquid directional transportation, and shipping due to their robust superhydrophobic properties and stable drag reduction effect.

Droplet splitting technology on open digital microfluidic platforms still faces significant challenges in terms of process complexity, the degree of automation, and operating conditions, which hinder its further development. This study proposes a fully automated method for precise droplet splitting based on printed circuit boards with open-coplanar asymmetric electrodes and a slippery liquid-infused porous surface. This method uses simple square electrodes arranged in a 3 × 5 array, combined with low-adhesion blade-assisted cutting and electrowetting-on-dielectric to drive droplet splitting, enabling accurate, stable, and repeatable automated droplet splitting on an open digital microfluidic platform. It has the advantages of a simple method, easy maintenance and integration, and high automation. This study systematically investigated the effects of droplet volume, applied voltage, blade thickness, cutting speed, and electrode shape on droplet splitting performance. We developed an active droplet position calibration method based on a simple 3 × 3 square electrode array combined with an enveloping voltage configuration strategy. For droplets with a volume of 10 μL, the positioning error can be controlled to within 0.06 mm, representing a reduction of more than 95% compared to the conventional EWOD free drive method. The experimental results show that to achieve stable and approximately equal-volume droplet splitting, the cutting speed needs to exceed the critical value related to the blade thickness. Among the square, zigzag, and hexagonal electrode shapes tested, the square electrode required the lowest splitting voltage. When the blade thickness is 0.3 mm, the droplets can be successfully split at a minimum voltage of 165 V. After increasing the splitting voltage to 400 V, the droplet splitting time was reduced from 5.57 s to 0.27 s, with a reduction of 95.2%, which significantly improves droplet splitting efficiency. This method provides a practical, stable, automated, and precise droplet splitting method for sample preparation, biochemical reactions, and portable droplet analysis systems.