Femtosecond laser-scribed superhydrophilic/superhydrophobic self-splitting patterns for one droplet multi-detection.

Superwettable patterned composite surfaces are being recognized as essential components in the field of precise droplet manipulation. However, developing simple and effective methods for manufacturing such surfaces remains a challenge especially for multi-detection surfaces. Here we present a femtosecond laser-based method to create a superhydrophobic/superhydrophilic (SHB/SHL) self-splitting pattern on a polyimide film to achieve droplet multi-detection. The mechanism behind droplet self-splitting on the SHB/SHL pattern surface is related to the dynamic behaviors of liquid recoiling and spreading. This behavior was affected by two main factors, including the width of the SHB stripe, and the radius of the SHL pattern. When the characteristic width is larger than 0.2, droplets are able to fully self-split. Furthermore, the SHB/SHL pattern can be utilized for alcohol detection and multiple biological tests performed using a single drop of biological fluid. This work provides a facile strategy for precise separation and distribution of microdroplets, and potentially could be applied in fluid recognition, biological screening, and combinatorial analysis.